Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize configurable as flexible requirement about SW-IOMMU.

Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize configurable as flexible requirement about SW-IOMMU.

[Paul Bolle]

This needs
    From: Wang, Xiaoming <xiaoming.wang@intel.com>

at the top of the message to comply with real name policy for patches.

On Fri, 2015-02-06 at 07:01 +0800, xiaomin1 wrote:
> The maximum of SW-IOMMU is limited to 2^11*128 = 256K.
> While in different platform and different requirements this seems improper.
> So modify the IO_TLB_SEGSIZE to io_tlb_segsize as configurable is make sense.
> 
> Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com>
> Signed-off-by: Zhang Dongxing <dongxing.zhang@intel.com>
> Signed-off-by: xiaomin1 <xiaoming.wang@intel.com>

And please edit that name here too. Or did you change your name after
submitting your previous patches?

> ---

This is a v2. So the subject should contain something like '[PATCH v2]'.
And it's nice to have a short list of changes here, below the ---
marker, so people can see what changed since v1.

Anyhow, I _think_ you took my comments on v1 into account. And by now
there's little in this patch that I could say anything interesting
about, so I don't really care that much.

Thanks,


Paul Bolle

>  arch/mips/cavium-octeon/dma-octeon.c |    2 +-
>  arch/mips/netlogic/common/nlm-dma.c  |    2 +-
>  drivers/xen/swiotlb-xen.c            |    6 +++---
>  include/linux/swiotlb.h              |    8 +------
>  lib/swiotlb.c                        |   39 ++++++++++++++++++++++++----------
>  5 files changed, 34 insertions(+), 23 deletions(-)
> 
> diff --git a/arch/mips/cavium-octeon/dma-octeon.c b/arch/mips/cavium-octeon/dma-octeon.c
> index 3778655..a521af6 100644
> --- a/arch/mips/cavium-octeon/dma-octeon.c
> +++ b/arch/mips/cavium-octeon/dma-octeon.c
> @@ -312,7 +312,7 @@ void __init plat_swiotlb_setup(void)
>  		swiotlbsize = 64 * (1<<20);
>  #endif
>  	swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> -	swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> +	swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
>  	swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
>  
>  	octeon_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> diff --git a/arch/mips/netlogic/common/nlm-dma.c b/arch/mips/netlogic/common/nlm-dma.c
> index f3d4ae8..eeffa8f 100644
> --- a/arch/mips/netlogic/common/nlm-dma.c
> +++ b/arch/mips/netlogic/common/nlm-dma.c
> @@ -99,7 +99,7 @@ void __init plat_swiotlb_setup(void)
>  
>  	swiotlbsize = 1 << 20; /* 1 MB for now */
>  	swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> -	swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> +	swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
>  	swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
>  
>  	nlm_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index 810ad41..3b3e9fe 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -164,11 +164,11 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
>  	dma_addr_t dma_handle;
>  	phys_addr_t p = virt_to_phys(buf);
>  
> -	dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) + PAGE_SHIFT;
> +	dma_bits = get_order(io_tlb_segsize << IO_TLB_SHIFT) + PAGE_SHIFT;
>  
>  	i = 0;
>  	do {
> -		int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE);
> +		int slabs = min(nslabs - i, (unsigned long)io_tlb_segsize);
>  
>  		do {
>  			rc = xen_create_contiguous_region(
> @@ -187,7 +187,7 @@ static unsigned long xen_set_nslabs(unsigned long nr_tbl)
>  {
>  	if (!nr_tbl) {
>  		xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
> -		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE);
> +		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, io_tlb_segsize);
>  	} else
>  		xen_io_tlb_nslabs = nr_tbl;
>  
> diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
> index e7a018e..13506db 100644
> --- a/include/linux/swiotlb.h
> +++ b/include/linux/swiotlb.h
> @@ -8,13 +8,7 @@ struct dma_attrs;
>  struct scatterlist;
>  
>  extern int swiotlb_force;
> -
> -/*
> - * Maximum allowable number of contiguous slabs to map,
> - * must be a power of 2.  What is the appropriate value ?
> - * The complexity of {map,unmap}_single is linearly dependent on this value.
> - */
> -#define IO_TLB_SEGSIZE	128
> +extern int io_tlb_segsize;
>  
>  /*
>   * log of the size of each IO TLB slab.  The number of slabs is command line
> diff --git a/lib/swiotlb.c b/lib/swiotlb.c
> index 4abda07..50c415a 100644
> --- a/lib/swiotlb.c
> +++ b/lib/swiotlb.c
> @@ -56,6 +56,15 @@
>  int swiotlb_force;
>  
>  /*
> + * Maximum allowable number of contiguous slabs to map,
> + * must be a power of 2.  What is the appropriate value ?
> + * define io_tlb_segsize as a parameter
> + * which can be changed dynamically in config file for special usage.
> + * The complexity of {map,unmap}_single is linearly dependent on this value.
> + */
> +int io_tlb_segsize = 128;
> +
> +/*
>   * Used to do a quick range check in swiotlb_tbl_unmap_single and
>   * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this
>   * API.
> @@ -97,12 +106,20 @@ static DEFINE_SPINLOCK(io_tlb_lock);
>  static int late_alloc;
>  
>  static int __init
> +setup_io_tlb_segsize(char *str)
> +{
> +	get_option(&str, &io_tlb_segsize);
> +	return 0;
> +}
> +__setup("io_tlb_segsize=", setup_io_tlb_segsize);
> +
> +static int __init
>  setup_io_tlb_npages(char *str)
>  {
>  	if (isdigit(*str)) {
>  		io_tlb_nslabs = simple_strtoul(str, &str, 0);
> -		/* avoid tail segment of size < IO_TLB_SEGSIZE */
> -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> +		/* avoid tail segment of size < io_tlb_segsize */
> +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
>  	}
>  	if (*str == ',')
>  		++str;
> @@ -183,7 +200,7 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
>  
>  	/*
>  	 * Allocate and initialize the free list array.  This array is used
> -	 * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
> +	 * to find contiguous free memory regions of size up to io_tlb_segsize
>  	 * between io_tlb_start and io_tlb_end.
>  	 */
>  	io_tlb_list = memblock_virt_alloc(
> @@ -193,7 +210,7 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
>  				PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)),
>  				PAGE_SIZE);
>  	for (i = 0; i < io_tlb_nslabs; i++) {
> -		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
> +		io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
>  		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
>  	}
>  	io_tlb_index = 0;
> @@ -217,7 +234,7 @@ swiotlb_init(int verbose)
>  
>  	if (!io_tlb_nslabs) {
>  		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
>  	}
>  
>  	bytes = io_tlb_nslabs << IO_TLB_SHIFT;
> @@ -249,7 +266,7 @@ swiotlb_late_init_with_default_size(size_t default_size)
>  
>  	if (!io_tlb_nslabs) {
>  		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
>  	}
>  
>  	/*
> @@ -308,7 +325,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
>  
>  	/*
>  	 * Allocate and initialize the free list array.  This array is used
> -	 * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
> +	 * to find contiguous free memory regions of size up to io_tlb_segsize
>  	 * between io_tlb_start and io_tlb_end.
>  	 */
>  	io_tlb_list = (unsigned int *)__get_free_pages(GFP_KERNEL,
> @@ -324,7 +341,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
>  		goto cleanup4;
>  
>  	for (i = 0; i < io_tlb_nslabs; i++) {
> -		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
> +		io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
>  		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
>  	}
>  	io_tlb_index = 0;
> @@ -493,7 +510,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
>  
>  			for (i = index; i < (int) (index + nslots); i++)
>  				io_tlb_list[i] = 0;
> -			for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE - 1) && io_tlb_list[i]; i--)
> +			for (i = index - 1; (OFFSET(i, io_tlb_segsize) != io_tlb_segsize - 1) && io_tlb_list[i]; i--)
>  				io_tlb_list[i] = ++count;
>  			tlb_addr = io_tlb_start + (index << IO_TLB_SHIFT);
>  
> @@ -571,7 +588,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
>  	 */
>  	spin_lock_irqsave(&io_tlb_lock, flags);
>  	{
> -		count = ((index + nslots) < ALIGN(index + 1, IO_TLB_SEGSIZE) ?
> +		count = ((index + nslots) < ALIGN(index + 1, io_tlb_segsize) ?
>  			 io_tlb_list[index + nslots] : 0);
>  		/*
>  		 * Step 1: return the slots to the free list, merging the
> @@ -585,7 +602,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
>  		 * Step 2: merge the returned slots with the preceding slots,
>  		 * if available (non zero)
>  		 */
> -		for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
> +		for (i = index - 1; (OFFSET(i, io_tlb_segsize) != io_tlb_segsize -1) && io_tlb_list[i]; i--)
>  			io_tlb_list[i] = ++count;
>  	}
>  	spin_unlock_irqrestore(&io_tlb_lock, flags);

Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize configurable as flexible requirement about SW-IOMMU.

[Konrad Rzeszutek Wilk]

On Fri, Feb 06, 2015 at 07:01:14AM +0800, xiaomin1 wrote:
> The maximum of SW-IOMMU is limited to 2^11*128 = 256K.
> While in different platform and different requirements this seems improper.
> So modify the IO_TLB_SEGSIZE to io_tlb_segsize as configurable is make sense.

More details please. What is the issue you are hitting?

> 
> Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com>
> Signed-off-by: Zhang Dongxing <dongxing.zhang@intel.com>
> Signed-off-by: xiaomin1 <xiaoming.wang@intel.com>
> ---
>  arch/mips/cavium-octeon/dma-octeon.c |    2 +-
>  arch/mips/netlogic/common/nlm-dma.c  |    2 +-
>  drivers/xen/swiotlb-xen.c            |    6 +++---
>  include/linux/swiotlb.h              |    8 +------
>  lib/swiotlb.c                        |   39 ++++++++++++++++++++++++----------
>  5 files changed, 34 insertions(+), 23 deletions(-)
> 
> diff --git a/arch/mips/cavium-octeon/dma-octeon.c b/arch/mips/cavium-octeon/dma-octeon.c
> index 3778655..a521af6 100644
> --- a/arch/mips/cavium-octeon/dma-octeon.c
> +++ b/arch/mips/cavium-octeon/dma-octeon.c
> @@ -312,7 +312,7 @@ void __init plat_swiotlb_setup(void)
>  		swiotlbsize = 64 * (1<<20);
>  #endif
>  	swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> -	swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> +	swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
>  	swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
>  
>  	octeon_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> diff --git a/arch/mips/netlogic/common/nlm-dma.c b/arch/mips/netlogic/common/nlm-dma.c
> index f3d4ae8..eeffa8f 100644
> --- a/arch/mips/netlogic/common/nlm-dma.c
> +++ b/arch/mips/netlogic/common/nlm-dma.c
> @@ -99,7 +99,7 @@ void __init plat_swiotlb_setup(void)
>  
>  	swiotlbsize = 1 << 20; /* 1 MB for now */
>  	swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> -	swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> +	swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
>  	swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
>  
>  	nlm_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index 810ad41..3b3e9fe 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -164,11 +164,11 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
>  	dma_addr_t dma_handle;
>  	phys_addr_t p = virt_to_phys(buf);
>  
> -	dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) + PAGE_SHIFT;
> +	dma_bits = get_order(io_tlb_segsize << IO_TLB_SHIFT) + PAGE_SHIFT;
>  
>  	i = 0;
>  	do {
> -		int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE);
> +		int slabs = min(nslabs - i, (unsigned long)io_tlb_segsize);
>  
>  		do {
>  			rc = xen_create_contiguous_region(
> @@ -187,7 +187,7 @@ static unsigned long xen_set_nslabs(unsigned long nr_tbl)
>  {
>  	if (!nr_tbl) {
>  		xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
> -		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE);
> +		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, io_tlb_segsize);
>  	} else
>  		xen_io_tlb_nslabs = nr_tbl;
>  
> diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
> index e7a018e..13506db 100644
> --- a/include/linux/swiotlb.h
> +++ b/include/linux/swiotlb.h
> @@ -8,13 +8,7 @@ struct dma_attrs;
>  struct scatterlist;
>  
>  extern int swiotlb_force;
> -
> -/*
> - * Maximum allowable number of contiguous slabs to map,
> - * must be a power of 2.  What is the appropriate value ?
> - * The complexity of {map,unmap}_single is linearly dependent on this value.
> - */
> -#define IO_TLB_SEGSIZE	128
> +extern int io_tlb_segsize;
>  
>  /*
>   * log of the size of each IO TLB slab.  The number of slabs is command line
> diff --git a/lib/swiotlb.c b/lib/swiotlb.c
> index 4abda07..50c415a 100644
> --- a/lib/swiotlb.c
> +++ b/lib/swiotlb.c
> @@ -56,6 +56,15 @@
>  int swiotlb_force;
>  
>  /*
> + * Maximum allowable number of contiguous slabs to map,
> + * must be a power of 2.  What is the appropriate value ?
> + * define io_tlb_segsize as a parameter
> + * which can be changed dynamically in config file for special usage.
> + * The complexity of {map,unmap}_single is linearly dependent on this value.
> + */
> +int io_tlb_segsize = 128;
> +
> +/*
>   * Used to do a quick range check in swiotlb_tbl_unmap_single and
>   * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this
>   * API.
> @@ -97,12 +106,20 @@ static DEFINE_SPINLOCK(io_tlb_lock);
>  static int late_alloc;
>  
>  static int __init
> +setup_io_tlb_segsize(char *str)
> +{
> +	get_option(&str, &io_tlb_segsize);
> +	return 0;
> +}
> +__setup("io_tlb_segsize=", setup_io_tlb_segsize);
> +
> +static int __init
>  setup_io_tlb_npages(char *str)
>  {
>  	if (isdigit(*str)) {
>  		io_tlb_nslabs = simple_strtoul(str, &str, 0);
> -		/* avoid tail segment of size < IO_TLB_SEGSIZE */
> -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> +		/* avoid tail segment of size < io_tlb_segsize */
> +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
>  	}
>  	if (*str == ',')
>  		++str;
> @@ -183,7 +200,7 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
>  
>  	/*
>  	 * Allocate and initialize the free list array.  This array is used
> -	 * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
> +	 * to find contiguous free memory regions of size up to io_tlb_segsize
>  	 * between io_tlb_start and io_tlb_end.
>  	 */
>  	io_tlb_list = memblock_virt_alloc(
> @@ -193,7 +210,7 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
>  				PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)),
>  				PAGE_SIZE);
>  	for (i = 0; i < io_tlb_nslabs; i++) {
> -		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
> +		io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
>  		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
>  	}
>  	io_tlb_index = 0;
> @@ -217,7 +234,7 @@ swiotlb_init(int verbose)
>  
>  	if (!io_tlb_nslabs) {
>  		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
>  	}
>  
>  	bytes = io_tlb_nslabs << IO_TLB_SHIFT;
> @@ -249,7 +266,7 @@ swiotlb_late_init_with_default_size(size_t default_size)
>  
>  	if (!io_tlb_nslabs) {
>  		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
>  	}
>  
>  	/*
> @@ -308,7 +325,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
>  
>  	/*
>  	 * Allocate and initialize the free list array.  This array is used
> -	 * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
> +	 * to find contiguous free memory regions of size up to io_tlb_segsize
>  	 * between io_tlb_start and io_tlb_end.
>  	 */
>  	io_tlb_list = (unsigned int *)__get_free_pages(GFP_KERNEL,
> @@ -324,7 +341,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
>  		goto cleanup4;
>  
>  	for (i = 0; i < io_tlb_nslabs; i++) {
> -		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
> +		io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
>  		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
>  	}
>  	io_tlb_index = 0;
> @@ -493,7 +510,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
>  
>  			for (i = index; i < (int) (index + nslots); i++)
>  				io_tlb_list[i] = 0;
> -			for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE - 1) && io_tlb_list[i]; i--)
> +			for (i = index - 1; (OFFSET(i, io_tlb_segsize) != io_tlb_segsize - 1) && io_tlb_list[i]; i--)
>  				io_tlb_list[i] = ++count;
>  			tlb_addr = io_tlb_start + (index << IO_TLB_SHIFT);
>  
> @@ -571,7 +588,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
>  	 */
>  	spin_lock_irqsave(&io_tlb_lock, flags);
>  	{
> -		count = ((index + nslots) < ALIGN(index + 1, IO_TLB_SEGSIZE) ?
> +		count = ((index + nslots) < ALIGN(index + 1, io_tlb_segsize) ?
>  			 io_tlb_list[index + nslots] : 0);
>  		/*
>  		 * Step 1: return the slots to the free list, merging the
> @@ -585,7 +602,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
>  		 * Step 2: merge the returned slots with the preceding slots,
>  		 * if available (non zero)
>  		 */
> -		for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
> +		for (i = index - 1; (OFFSET(i, io_tlb_segsize) != io_tlb_segsize -1) && io_tlb_list[i]; i--)
>  			io_tlb_list[i] = ++count;
>  	}
>  	spin_unlock_irqrestore(&io_tlb_lock, flags);
> -- 
> 1.7.9.5
> 

[PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize configurable as flexible requirement about SW-IOMMU.

[xiaomin1]

The maximum of SW-IOMMU is limited to 2^11*128 = 256K.
While in different platform and different requirements this seems improper.
So modify the IO_TLB_SEGSIZE to io_tlb_segsize as configurable is make sense.

Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com>
Signed-off-by: Zhang Dongxing <dongxing.zhang@intel.com>
Signed-off-by: xiaomin1 <xiaoming.wang@intel.com>
---
 arch/mips/cavium-octeon/dma-octeon.c |    2 +-
 arch/mips/netlogic/common/nlm-dma.c  |    2 +-
 drivers/xen/swiotlb-xen.c            |    6 +++---
 include/linux/swiotlb.h              |    8 +------
 lib/swiotlb.c                        |   39 ++++++++++++++++++++++++----------
 5 files changed, 34 insertions(+), 23 deletions(-)

diff --git a/arch/mips/cavium-octeon/dma-octeon.c b/arch/mips/cavium-octeon/dma-octeon.c
index 3778655..a521af6 100644
--- a/arch/mips/cavium-octeon/dma-octeon.c
+++ b/arch/mips/cavium-octeon/dma-octeon.c
@@ -312,7 +312,7 @@ void __init plat_swiotlb_setup(void)
 		swiotlbsize = 64 * (1<<20);
 #endif
 	swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
-	swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
+	swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
 	swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
 
 	octeon_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
diff --git a/arch/mips/netlogic/common/nlm-dma.c b/arch/mips/netlogic/common/nlm-dma.c
index f3d4ae8..eeffa8f 100644
--- a/arch/mips/netlogic/common/nlm-dma.c
+++ b/arch/mips/netlogic/common/nlm-dma.c
@@ -99,7 +99,7 @@ void __init plat_swiotlb_setup(void)
 
 	swiotlbsize = 1 << 20; /* 1 MB for now */
 	swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
-	swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
+	swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
 	swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
 
 	nlm_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 810ad41..3b3e9fe 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -164,11 +164,11 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
 	dma_addr_t dma_handle;
 	phys_addr_t p = virt_to_phys(buf);
 
-	dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) + PAGE_SHIFT;
+	dma_bits = get_order(io_tlb_segsize << IO_TLB_SHIFT) + PAGE_SHIFT;
 
 	i = 0;
 	do {
-		int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE);
+		int slabs = min(nslabs - i, (unsigned long)io_tlb_segsize);
 
 		do {
 			rc = xen_create_contiguous_region(
@@ -187,7 +187,7 @@ static unsigned long xen_set_nslabs(unsigned long nr_tbl)
 {
 	if (!nr_tbl) {
 		xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
-		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE);
+		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, io_tlb_segsize);
 	} else
 		xen_io_tlb_nslabs = nr_tbl;
 
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index e7a018e..13506db 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -8,13 +8,7 @@ struct dma_attrs;
 struct scatterlist;
 
 extern int swiotlb_force;
-
-/*
- * Maximum allowable number of contiguous slabs to map,
- * must be a power of 2.  What is the appropriate value ?
- * The complexity of {map,unmap}_single is linearly dependent on this value.
- */
-#define IO_TLB_SEGSIZE	128
+extern int io_tlb_segsize;
 
 /*
  * log of the size of each IO TLB slab.  The number of slabs is command line
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 4abda07..50c415a 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -56,6 +56,15 @@
 int swiotlb_force;
 
 /*
+ * Maximum allowable number of contiguous slabs to map,
+ * must be a power of 2.  What is the appropriate value ?
+ * define io_tlb_segsize as a parameter
+ * which can be changed dynamically in config file for special usage.
+ * The complexity of {map,unmap}_single is linearly dependent on this value.
+ */
+int io_tlb_segsize = 128;
+
+/*
  * Used to do a quick range check in swiotlb_tbl_unmap_single and
  * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this
  * API.
@@ -97,12 +106,20 @@ static DEFINE_SPINLOCK(io_tlb_lock);
 static int late_alloc;
 
 static int __init
+setup_io_tlb_segsize(char *str)
+{
+	get_option(&str, &io_tlb_segsize);
+	return 0;
+}
+__setup("io_tlb_segsize=", setup_io_tlb_segsize);
+
+static int __init
 setup_io_tlb_npages(char *str)
 {
 	if (isdigit(*str)) {
 		io_tlb_nslabs = simple_strtoul(str, &str, 0);
-		/* avoid tail segment of size < IO_TLB_SEGSIZE */
-		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
+		/* avoid tail segment of size < io_tlb_segsize */
+		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
 	}
 	if (*str == ',')
 		++str;
@@ -183,7 +200,7 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
 
 	/*
 	 * Allocate and initialize the free list array.  This array is used
-	 * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
+	 * to find contiguous free memory regions of size up to io_tlb_segsize
 	 * between io_tlb_start and io_tlb_end.
 	 */
 	io_tlb_list = memblock_virt_alloc(
@@ -193,7 +210,7 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
 				PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)),
 				PAGE_SIZE);
 	for (i = 0; i < io_tlb_nslabs; i++) {
-		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
+		io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
 		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
 	}
 	io_tlb_index = 0;
@@ -217,7 +234,7 @@ swiotlb_init(int verbose)
 
 	if (!io_tlb_nslabs) {
 		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
-		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
+		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
 	}
 
 	bytes = io_tlb_nslabs << IO_TLB_SHIFT;
@@ -249,7 +266,7 @@ swiotlb_late_init_with_default_size(size_t default_size)
 
 	if (!io_tlb_nslabs) {
 		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
-		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
+		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
 	}
 
 	/*
@@ -308,7 +325,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
 
 	/*
 	 * Allocate and initialize the free list array.  This array is used
-	 * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
+	 * to find contiguous free memory regions of size up to io_tlb_segsize
 	 * between io_tlb_start and io_tlb_end.
 	 */
 	io_tlb_list = (unsigned int *)__get_free_pages(GFP_KERNEL,
@@ -324,7 +341,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
 		goto cleanup4;
 
 	for (i = 0; i < io_tlb_nslabs; i++) {
-		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
+		io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
 		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
 	}
 	io_tlb_index = 0;
@@ -493,7 +510,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
 
 			for (i = index; i < (int) (index + nslots); i++)
 				io_tlb_list[i] = 0;
-			for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE - 1) && io_tlb_list[i]; i--)
+			for (i = index - 1; (OFFSET(i, io_tlb_segsize) != io_tlb_segsize - 1) && io_tlb_list[i]; i--)
 				io_tlb_list[i] = ++count;
 			tlb_addr = io_tlb_start + (index << IO_TLB_SHIFT);
 
@@ -571,7 +588,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
 	 */
 	spin_lock_irqsave(&io_tlb_lock, flags);
 	{
-		count = ((index + nslots) < ALIGN(index + 1, IO_TLB_SEGSIZE) ?
+		count = ((index + nslots) < ALIGN(index + 1, io_tlb_segsize) ?
 			 io_tlb_list[index + nslots] : 0);
 		/*
 		 * Step 1: return the slots to the free list, merging the
@@ -585,7 +602,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
 		 * Step 2: merge the returned slots with the preceding slots,
 		 * if available (non zero)
 		 */
-		for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
+		for (i = index - 1; (OFFSET(i, io_tlb_segsize) != io_tlb_segsize -1) && io_tlb_list[i]; i--)
 			io_tlb_list[i] = ++count;
 	}
 	spin_unlock_irqrestore(&io_tlb_lock, flags);
-- 
1.7.9.5

RE: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize configurable as flexible requirement about SW-IOMMU.

[Wang, Xiaoming]

> -----Original Message-----
> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@oracle.com]
> Sent: Friday, February 6, 2015 3:33 AM
> To: Wang, Xiaoming
> Cc: ralf@linux-mips.org; boris.ostrovsky@oracle.com;
> david.vrabel@citrix.com; linux-mips@linux-mips.org; linux-
> kernel@vger.kernel.org; xen-devel@lists.xenproject.org; akpm@linux-
> foundation.org; linux@horizon.com; lauraa@codeaurora.org;
> heiko.carstens@de.ibm.com; d.kasatkin@samsung.com;
> takahiro.akashi@linaro.org; chris@chris-wilson.co.uk; pebolle@tiscali.nl; Liu,
> Chuansheng; Zhang, Dongxing
> Subject: Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize
> configurable as flexible requirement about SW-IOMMU.
> 
> On Fri, Feb 06, 2015 at 07:01:14AM +0800, xiaomin1 wrote:
> > The maximum of SW-IOMMU is limited to 2^11*128 = 256K.
> > While in different platform and different requirements this seems improper.
> > So modify the IO_TLB_SEGSIZE to io_tlb_segsize as configurable is make
> sense.
> 
> More details please. What is the issue you are hitting?
> 
Example:
If 1M bytes are requied. There has an error like.
[   31.474769] dwc3_otg 0000:00:16.0: dwc3_intel_byt_notify_charger_type(): dwc3_intel_byt_notify_charger_type: invalid SDP current!
[   31.554077] android_work: sent uevent USB_STATE=CONNECTED
[   31.564244] android_usb gadget: high-speed config #1: android
[   31.571468] android_work: sent uevent USB_STATE=CONFIGURED
[   31.942738] DMA: Out of SW-IOMMU space for 1048576 bytes at device gadget
[   31.950345] Kernel panic - not syncing: DMA: Random memory could be DMA written
[   31.950345] 
[   31.960170] CPU: 1 PID: 172 Comm: droidboot Tainted: G        W    3.10.20-x86_64_byt-g1077f87 #2
[   31.970086] Hardware name: Intel Corp. VALLEYVIEW C0 PLATFORM/BYT-T FFD8, BIOS BLADE_21.X64.0004.R14.1412311144 FFD8_X64_R_2014_12_31_1151 12/31/2014
[   31.985053]  0000000000100000 ffff880136c2fc98 ffffffff82967d45 ffff880136c2fd10
[   31.993327]  ffffffff82961761 0000000000000008 ffff880136c2fd20 ffff880136c2fcc0
[   32.001590]  ffffffff829618fb 0000000000000002 ffffffff820aeff9 0000000000008d8c
[   32.009871] Call Trace:
[   32.012610]  [<ffffffff82967d45>] dump_stack+0x19/0x1b
[   32.018353]  [<ffffffff82961761>] panic+0xc8/0x1d6
[   32.023707]  [<ffffffff829618fb>] ? printk+0x55/0x57
[   32.029258]  [<ffffffff820aeff9>] ? console_unlock+0x1f9/0x460
[   32.035772]  [<ffffffff82347cbe>] swiotlb_map_page+0x12e/0x140
[   32.042283]  [<ffffffff82599d4d>] usb_gadget_map_request+0x16d/0x220
[   32.049387]  [<ffffffff8255ce89>] dwc3_gadget_ep_queue+0x229/0x460
[   32.056297]  [<ffffffff825b4624>] ffs_epfile_io.isra.96+0x3e4/0x520
[   32.063296]  [<ffffffff820e438d>] ? get_parent_ip+0xd/0x50
[   32.069427]  [<ffffffff82975a61>] ? sub_preempt_count+0x71/0x100
[   32.076142]  [<ffffffff825b47b8>] ffs_epfile_read+0x28/0x30
[   32.082370]  [<ffffffff821b6b8c>] vfs_read+0x9c/0x170
[   32.088014]  [<ffffffff821b765d>] SyS_read+0x4d/0xa0
[   32.093562]  [<ffffffff8297b179>] ia32_do_call+0x13/0x13
> >
> > Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com>
> > Signed-off-by: Zhang Dongxing <dongxing.zhang@intel.com>
> > Signed-off-by: xiaomin1 <xiaoming.wang@intel.com>
> > ---
> >  arch/mips/cavium-octeon/dma-octeon.c |    2 +-
> >  arch/mips/netlogic/common/nlm-dma.c  |    2 +-
> >  drivers/xen/swiotlb-xen.c            |    6 +++---
> >  include/linux/swiotlb.h              |    8 +------
> >  lib/swiotlb.c                        |   39 ++++++++++++++++++++++++----------
> >  5 files changed, 34 insertions(+), 23 deletions(-)
> >
> > diff --git a/arch/mips/cavium-octeon/dma-octeon.c
> > b/arch/mips/cavium-octeon/dma-octeon.c
> > index 3778655..a521af6 100644
> > --- a/arch/mips/cavium-octeon/dma-octeon.c
> > +++ b/arch/mips/cavium-octeon/dma-octeon.c
> > @@ -312,7 +312,7 @@ void __init plat_swiotlb_setup(void)
> >  		swiotlbsize = 64 * (1<<20);
> >  #endif
> >  	swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> > -	swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> > +	swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
> >  	swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
> >
> >  	octeon_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> > diff --git a/arch/mips/netlogic/common/nlm-dma.c
> > b/arch/mips/netlogic/common/nlm-dma.c
> > index f3d4ae8..eeffa8f 100644
> > --- a/arch/mips/netlogic/common/nlm-dma.c
> > +++ b/arch/mips/netlogic/common/nlm-dma.c
> > @@ -99,7 +99,7 @@ void __init plat_swiotlb_setup(void)
> >
> >  	swiotlbsize = 1 << 20; /* 1 MB for now */
> >  	swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> > -	swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> > +	swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
> >  	swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
> >
> >  	nlm_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> > index 810ad41..3b3e9fe 100644
> > --- a/drivers/xen/swiotlb-xen.c
> > +++ b/drivers/xen/swiotlb-xen.c
> > @@ -164,11 +164,11 @@ xen_swiotlb_fixup(void *buf, size_t size,
> unsigned long nslabs)
> >  	dma_addr_t dma_handle;
> >  	phys_addr_t p = virt_to_phys(buf);
> >
> > -	dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) +
> PAGE_SHIFT;
> > +	dma_bits = get_order(io_tlb_segsize << IO_TLB_SHIFT) + PAGE_SHIFT;
> >
> >  	i = 0;
> >  	do {
> > -		int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE);
> > +		int slabs = min(nslabs - i, (unsigned long)io_tlb_segsize);
> >
> >  		do {
> >  			rc = xen_create_contiguous_region( @@ -187,7
> +187,7 @@ static
> > unsigned long xen_set_nslabs(unsigned long nr_tbl)  {
> >  	if (!nr_tbl) {
> >  		xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
> > -		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs,
> IO_TLB_SEGSIZE);
> > +		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, io_tlb_segsize);
> >  	} else
> >  		xen_io_tlb_nslabs = nr_tbl;
> >
> > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index
> > e7a018e..13506db 100644
> > --- a/include/linux/swiotlb.h
> > +++ b/include/linux/swiotlb.h
> > @@ -8,13 +8,7 @@ struct dma_attrs;
> >  struct scatterlist;
> >
> >  extern int swiotlb_force;
> > -
> > -/*
> > - * Maximum allowable number of contiguous slabs to map,
> > - * must be a power of 2.  What is the appropriate value ?
> > - * The complexity of {map,unmap}_single is linearly dependent on this
> value.
> > - */
> > -#define IO_TLB_SEGSIZE	128
> > +extern int io_tlb_segsize;
> >
> >  /*
> >   * log of the size of each IO TLB slab.  The number of slabs is
> > command line diff --git a/lib/swiotlb.c b/lib/swiotlb.c index
> > 4abda07..50c415a 100644
> > --- a/lib/swiotlb.c
> > +++ b/lib/swiotlb.c
> > @@ -56,6 +56,15 @@
> >  int swiotlb_force;
> >
> >  /*
> > + * Maximum allowable number of contiguous slabs to map,
> > + * must be a power of 2.  What is the appropriate value ?
> > + * define io_tlb_segsize as a parameter
> > + * which can be changed dynamically in config file for special usage.
> > + * The complexity of {map,unmap}_single is linearly dependent on this
> value.
> > + */
> > +int io_tlb_segsize = 128;
> > +
> > +/*
> >   * Used to do a quick range check in swiotlb_tbl_unmap_single and
> >   * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by
> this
> >   * API.
> > @@ -97,12 +106,20 @@ static DEFINE_SPINLOCK(io_tlb_lock);  static int
> > late_alloc;
> >
> >  static int __init
> > +setup_io_tlb_segsize(char *str)
> > +{
> > +	get_option(&str, &io_tlb_segsize);
> > +	return 0;
> > +}
> > +__setup("io_tlb_segsize=", setup_io_tlb_segsize);
> > +
> > +static int __init
> >  setup_io_tlb_npages(char *str)
> >  {
> >  	if (isdigit(*str)) {
> >  		io_tlb_nslabs = simple_strtoul(str, &str, 0);
> > -		/* avoid tail segment of size < IO_TLB_SEGSIZE */
> > -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > +		/* avoid tail segment of size < io_tlb_segsize */
> > +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> >  	}
> >  	if (*str == ',')
> >  		++str;
> > @@ -183,7 +200,7 @@ int __init swiotlb_init_with_tbl(char *tlb,
> > unsigned long nslabs, int verbose)
> >
> >  	/*
> >  	 * Allocate and initialize the free list array.  This array is used
> > -	 * to find contiguous free memory regions of size up to
> IO_TLB_SEGSIZE
> > +	 * to find contiguous free memory regions of size up to
> > +io_tlb_segsize
> >  	 * between io_tlb_start and io_tlb_end.
> >  	 */
> >  	io_tlb_list = memblock_virt_alloc(
> > @@ -193,7 +210,7 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned
> long nslabs, int verbose)
> >  				PAGE_ALIGN(io_tlb_nslabs *
> sizeof(phys_addr_t)),
> >  				PAGE_SIZE);
> >  	for (i = 0; i < io_tlb_nslabs; i++) {
> > -		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
> > +		io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
> >  		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> >  	}
> >  	io_tlb_index = 0;
> > @@ -217,7 +234,7 @@ swiotlb_init(int verbose)
> >
> >  	if (!io_tlb_nslabs) {
> >  		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> >  	}
> >
> >  	bytes = io_tlb_nslabs << IO_TLB_SHIFT; @@ -249,7 +266,7 @@
> > swiotlb_late_init_with_default_size(size_t default_size)
> >
> >  	if (!io_tlb_nslabs) {
> >  		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> >  	}
> >
> >  	/*
> > @@ -308,7 +325,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned
> > long nslabs)
> >
> >  	/*
> >  	 * Allocate and initialize the free list array.  This array is used
> > -	 * to find contiguous free memory regions of size up to
> IO_TLB_SEGSIZE
> > +	 * to find contiguous free memory regions of size up to
> > +io_tlb_segsize
> >  	 * between io_tlb_start and io_tlb_end.
> >  	 */
> >  	io_tlb_list = (unsigned int *)__get_free_pages(GFP_KERNEL, @@ -
> 324,7
> > +341,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
> >  		goto cleanup4;
> >
> >  	for (i = 0; i < io_tlb_nslabs; i++) {
> > -		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
> > +		io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
> >  		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> >  	}
> >  	io_tlb_index = 0;
> > @@ -493,7 +510,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device
> > *hwdev,
> >
> >  			for (i = index; i < (int) (index + nslots); i++)
> >  				io_tlb_list[i] = 0;
> > -			for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) !=
> IO_TLB_SEGSIZE - 1) && io_tlb_list[i]; i--)
> > +			for (i = index - 1; (OFFSET(i, io_tlb_segsize) !=
> io_tlb_segsize -
> > +1) && io_tlb_list[i]; i--)
> >  				io_tlb_list[i] = ++count;
> >  			tlb_addr = io_tlb_start + (index << IO_TLB_SHIFT);
> >
> > @@ -571,7 +588,7 @@ void swiotlb_tbl_unmap_single(struct device
> *hwdev, phys_addr_t tlb_addr,
> >  	 */
> >  	spin_lock_irqsave(&io_tlb_lock, flags);
> >  	{
> > -		count = ((index + nslots) < ALIGN(index + 1, IO_TLB_SEGSIZE) ?
> > +		count = ((index + nslots) < ALIGN(index + 1, io_tlb_segsize) ?
> >  			 io_tlb_list[index + nslots] : 0);
> >  		/*
> >  		 * Step 1: return the slots to the free list, merging the @@ -
> 585,7
> > +602,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev,
> phys_addr_t tlb_addr,
> >  		 * Step 2: merge the returned slots with the preceding slots,
> >  		 * if available (non zero)
> >  		 */
> > -		for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) !=
> IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
> > +		for (i = index - 1; (OFFSET(i, io_tlb_segsize) != io_tlb_segsize
> > +-1) && io_tlb_list[i]; i--)
> >  			io_tlb_list[i] = ++count;
> >  	}
> >  	spin_unlock_irqrestore(&io_tlb_lock, flags);
> > --
> > 1.7.9.5
> >

Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize configurable as flexible requirement about SW-IOMMU.

[Konrad Rzeszutek Wilk]

On Fri, Feb 06, 2015 at 12:10:15AM +0000, Wang, Xiaoming wrote:
> 
> 
> > -----Original Message-----
> > From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@oracle.com]
> > Sent: Friday, February 6, 2015 3:33 AM
> > To: Wang, Xiaoming
> > Cc: ralf@linux-mips.org; boris.ostrovsky@oracle.com;
> > david.vrabel@citrix.com; linux-mips@linux-mips.org; linux-
> > kernel@vger.kernel.org; xen-devel@lists.xenproject.org; akpm@linux-
> > foundation.org; linux@horizon.com; lauraa@codeaurora.org;
> > heiko.carstens@de.ibm.com; d.kasatkin@samsung.com;
> > takahiro.akashi@linaro.org; chris@chris-wilson.co.uk; pebolle@tiscali.nl; Liu,
> > Chuansheng; Zhang, Dongxing
> > Subject: Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize
> > configurable as flexible requirement about SW-IOMMU.
> > 
> > On Fri, Feb 06, 2015 at 07:01:14AM +0800, xiaomin1 wrote:
> > > The maximum of SW-IOMMU is limited to 2^11*128 = 256K.
> > > While in different platform and different requirements this seems improper.
> > > So modify the IO_TLB_SEGSIZE to io_tlb_segsize as configurable is make
> > sense.
> > 
> > More details please. What is the issue you are hitting?
> > 
> Example:
> If 1M bytes are requied. There has an error like.

Ok, but even with 1MB size - you only have 64 'slots' (if you
allocate an 64MB buffer). And the other 'slots' can be fragmented
so you might still not have enough 1MB chunks available.

Do you have some thoughts on how that would be addressed?

> [   31.474769] dwc3_otg 0000:00:16.0: dwc3_intel_byt_notify_charger_type(): dwc3_intel_byt_notify_charger_type: invalid SDP current!
> [   31.554077] android_work: sent uevent USB_STATE=CONNECTED
> [   31.564244] android_usb gadget: high-speed config #1: android
> [   31.571468] android_work: sent uevent USB_STATE=CONFIGURED
> [   31.942738] DMA: Out of SW-IOMMU space for 1048576 bytes at device gadget
> [   31.950345] Kernel panic - not syncing: DMA: Random memory could be DMA written
> [   31.950345] 
> [   31.960170] CPU: 1 PID: 172 Comm: droidboot Tainted: G        W    3.10.20-x86_64_byt-g1077f87 #2
> [   31.970086] Hardware name: Intel Corp. VALLEYVIEW C0 PLATFORM/BYT-T FFD8, BIOS BLADE_21.X64.0004.R14.1412311144 FFD8_X64_R_2014_12_31_1151 12/31/2014
> [   31.985053]  0000000000100000 ffff880136c2fc98 ffffffff82967d45 ffff880136c2fd10
> [   31.993327]  ffffffff82961761 0000000000000008 ffff880136c2fd20 ffff880136c2fcc0
> [   32.001590]  ffffffff829618fb 0000000000000002 ffffffff820aeff9 0000000000008d8c
> [   32.009871] Call Trace:
> [   32.012610]  [<ffffffff82967d45>] dump_stack+0x19/0x1b
> [   32.018353]  [<ffffffff82961761>] panic+0xc8/0x1d6
> [   32.023707]  [<ffffffff829618fb>] ? printk+0x55/0x57
> [   32.029258]  [<ffffffff820aeff9>] ? console_unlock+0x1f9/0x460
> [   32.035772]  [<ffffffff82347cbe>] swiotlb_map_page+0x12e/0x140
> [   32.042283]  [<ffffffff82599d4d>] usb_gadget_map_request+0x16d/0x220
> [   32.049387]  [<ffffffff8255ce89>] dwc3_gadget_ep_queue+0x229/0x460
> [   32.056297]  [<ffffffff825b4624>] ffs_epfile_io.isra.96+0x3e4/0x520
> [   32.063296]  [<ffffffff820e438d>] ? get_parent_ip+0xd/0x50
> [   32.069427]  [<ffffffff82975a61>] ? sub_preempt_count+0x71/0x100
> [   32.076142]  [<ffffffff825b47b8>] ffs_epfile_read+0x28/0x30
> [   32.082370]  [<ffffffff821b6b8c>] vfs_read+0x9c/0x170
> [   32.088014]  [<ffffffff821b765d>] SyS_read+0x4d/0xa0
> [   32.093562]  [<ffffffff8297b179>] ia32_do_call+0x13/0x13
> > >
> > > Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com>
> > > Signed-off-by: Zhang Dongxing <dongxing.zhang@intel.com>
> > > Signed-off-by: xiaomin1 <xiaoming.wang@intel.com>
> > > ---
> > >  arch/mips/cavium-octeon/dma-octeon.c |    2 +-
> > >  arch/mips/netlogic/common/nlm-dma.c  |    2 +-
> > >  drivers/xen/swiotlb-xen.c            |    6 +++---
> > >  include/linux/swiotlb.h              |    8 +------
> > >  lib/swiotlb.c                        |   39 ++++++++++++++++++++++++----------
> > >  5 files changed, 34 insertions(+), 23 deletions(-)
> > >
> > > diff --git a/arch/mips/cavium-octeon/dma-octeon.c
> > > b/arch/mips/cavium-octeon/dma-octeon.c
> > > index 3778655..a521af6 100644
> > > --- a/arch/mips/cavium-octeon/dma-octeon.c
> > > +++ b/arch/mips/cavium-octeon/dma-octeon.c
> > > @@ -312,7 +312,7 @@ void __init plat_swiotlb_setup(void)
> > >  		swiotlbsize = 64 * (1<<20);
> > >  #endif
> > >  	swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> > > -	swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> > > +	swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
> > >  	swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
> > >
> > >  	octeon_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> > > diff --git a/arch/mips/netlogic/common/nlm-dma.c
> > > b/arch/mips/netlogic/common/nlm-dma.c
> > > index f3d4ae8..eeffa8f 100644
> > > --- a/arch/mips/netlogic/common/nlm-dma.c
> > > +++ b/arch/mips/netlogic/common/nlm-dma.c
> > > @@ -99,7 +99,7 @@ void __init plat_swiotlb_setup(void)
> > >
> > >  	swiotlbsize = 1 << 20; /* 1 MB for now */
> > >  	swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> > > -	swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> > > +	swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
> > >  	swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
> > >
> > >  	nlm_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> > > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> > > index 810ad41..3b3e9fe 100644
> > > --- a/drivers/xen/swiotlb-xen.c
> > > +++ b/drivers/xen/swiotlb-xen.c
> > > @@ -164,11 +164,11 @@ xen_swiotlb_fixup(void *buf, size_t size,
> > unsigned long nslabs)
> > >  	dma_addr_t dma_handle;
> > >  	phys_addr_t p = virt_to_phys(buf);
> > >
> > > -	dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) +
> > PAGE_SHIFT;
> > > +	dma_bits = get_order(io_tlb_segsize << IO_TLB_SHIFT) + PAGE_SHIFT;
> > >
> > >  	i = 0;
> > >  	do {
> > > -		int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE);
> > > +		int slabs = min(nslabs - i, (unsigned long)io_tlb_segsize);
> > >
> > >  		do {
> > >  			rc = xen_create_contiguous_region( @@ -187,7
> > +187,7 @@ static
> > > unsigned long xen_set_nslabs(unsigned long nr_tbl)  {
> > >  	if (!nr_tbl) {
> > >  		xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
> > > -		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs,
> > IO_TLB_SEGSIZE);
> > > +		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, io_tlb_segsize);
> > >  	} else
> > >  		xen_io_tlb_nslabs = nr_tbl;
> > >
> > > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index
> > > e7a018e..13506db 100644
> > > --- a/include/linux/swiotlb.h
> > > +++ b/include/linux/swiotlb.h
> > > @@ -8,13 +8,7 @@ struct dma_attrs;
> > >  struct scatterlist;
> > >
> > >  extern int swiotlb_force;
> > > -
> > > -/*
> > > - * Maximum allowable number of contiguous slabs to map,
> > > - * must be a power of 2.  What is the appropriate value ?
> > > - * The complexity of {map,unmap}_single is linearly dependent on this
> > value.
> > > - */
> > > -#define IO_TLB_SEGSIZE	128
> > > +extern int io_tlb_segsize;
> > >
> > >  /*
> > >   * log of the size of each IO TLB slab.  The number of slabs is
> > > command line diff --git a/lib/swiotlb.c b/lib/swiotlb.c index
> > > 4abda07..50c415a 100644
> > > --- a/lib/swiotlb.c
> > > +++ b/lib/swiotlb.c
> > > @@ -56,6 +56,15 @@
> > >  int swiotlb_force;
> > >
> > >  /*
> > > + * Maximum allowable number of contiguous slabs to map,
> > > + * must be a power of 2.  What is the appropriate value ?
> > > + * define io_tlb_segsize as a parameter
> > > + * which can be changed dynamically in config file for special usage.
> > > + * The complexity of {map,unmap}_single is linearly dependent on this
> > value.
> > > + */
> > > +int io_tlb_segsize = 128;
> > > +
> > > +/*
> > >   * Used to do a quick range check in swiotlb_tbl_unmap_single and
> > >   * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by
> > this
> > >   * API.
> > > @@ -97,12 +106,20 @@ static DEFINE_SPINLOCK(io_tlb_lock);  static int
> > > late_alloc;
> > >
> > >  static int __init
> > > +setup_io_tlb_segsize(char *str)
> > > +{
> > > +	get_option(&str, &io_tlb_segsize);
> > > +	return 0;
> > > +}
> > > +__setup("io_tlb_segsize=", setup_io_tlb_segsize);
> > > +
> > > +static int __init
> > >  setup_io_tlb_npages(char *str)
> > >  {
> > >  	if (isdigit(*str)) {
> > >  		io_tlb_nslabs = simple_strtoul(str, &str, 0);
> > > -		/* avoid tail segment of size < IO_TLB_SEGSIZE */
> > > -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > > +		/* avoid tail segment of size < io_tlb_segsize */
> > > +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> > >  	}
> > >  	if (*str == ',')
> > >  		++str;
> > > @@ -183,7 +200,7 @@ int __init swiotlb_init_with_tbl(char *tlb,
> > > unsigned long nslabs, int verbose)
> > >
> > >  	/*
> > >  	 * Allocate and initialize the free list array.  This array is used
> > > -	 * to find contiguous free memory regions of size up to
> > IO_TLB_SEGSIZE
> > > +	 * to find contiguous free memory regions of size up to
> > > +io_tlb_segsize
> > >  	 * between io_tlb_start and io_tlb_end.
> > >  	 */
> > >  	io_tlb_list = memblock_virt_alloc(
> > > @@ -193,7 +210,7 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned
> > long nslabs, int verbose)
> > >  				PAGE_ALIGN(io_tlb_nslabs *
> > sizeof(phys_addr_t)),
> > >  				PAGE_SIZE);
> > >  	for (i = 0; i < io_tlb_nslabs; i++) {
> > > -		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
> > > +		io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
> > >  		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> > >  	}
> > >  	io_tlb_index = 0;
> > > @@ -217,7 +234,7 @@ swiotlb_init(int verbose)
> > >
> > >  	if (!io_tlb_nslabs) {
> > >  		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > > -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > > +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> > >  	}
> > >
> > >  	bytes = io_tlb_nslabs << IO_TLB_SHIFT; @@ -249,7 +266,7 @@
> > > swiotlb_late_init_with_default_size(size_t default_size)
> > >
> > >  	if (!io_tlb_nslabs) {
> > >  		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > > -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > > +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> > >  	}
> > >
> > >  	/*
> > > @@ -308,7 +325,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned
> > > long nslabs)
> > >
> > >  	/*
> > >  	 * Allocate and initialize the free list array.  This array is used
> > > -	 * to find contiguous free memory regions of size up to
> > IO_TLB_SEGSIZE
> > > +	 * to find contiguous free memory regions of size up to
> > > +io_tlb_segsize
> > >  	 * between io_tlb_start and io_tlb_end.
> > >  	 */
> > >  	io_tlb_list = (unsigned int *)__get_free_pages(GFP_KERNEL, @@ -
> > 324,7
> > > +341,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
> > >  		goto cleanup4;
> > >
> > >  	for (i = 0; i < io_tlb_nslabs; i++) {
> > > -		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
> > > +		io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
> > >  		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> > >  	}
> > >  	io_tlb_index = 0;
> > > @@ -493,7 +510,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device
> > > *hwdev,
> > >
> > >  			for (i = index; i < (int) (index + nslots); i++)
> > >  				io_tlb_list[i] = 0;
> > > -			for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) !=
> > IO_TLB_SEGSIZE - 1) && io_tlb_list[i]; i--)
> > > +			for (i = index - 1; (OFFSET(i, io_tlb_segsize) !=
> > io_tlb_segsize -
> > > +1) && io_tlb_list[i]; i--)
> > >  				io_tlb_list[i] = ++count;
> > >  			tlb_addr = io_tlb_start + (index << IO_TLB_SHIFT);
> > >
> > > @@ -571,7 +588,7 @@ void swiotlb_tbl_unmap_single(struct device
> > *hwdev, phys_addr_t tlb_addr,
> > >  	 */
> > >  	spin_lock_irqsave(&io_tlb_lock, flags);
> > >  	{
> > > -		count = ((index + nslots) < ALIGN(index + 1, IO_TLB_SEGSIZE) ?
> > > +		count = ((index + nslots) < ALIGN(index + 1, io_tlb_segsize) ?
> > >  			 io_tlb_list[index + nslots] : 0);
> > >  		/*
> > >  		 * Step 1: return the slots to the free list, merging the @@ -
> > 585,7
> > > +602,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev,
> > phys_addr_t tlb_addr,
> > >  		 * Step 2: merge the returned slots with the preceding slots,
> > >  		 * if available (non zero)
> > >  		 */
> > > -		for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) !=
> > IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
> > > +		for (i = index - 1; (OFFSET(i, io_tlb_segsize) != io_tlb_segsize
> > > +-1) && io_tlb_list[i]; i--)
> > >  			io_tlb_list[i] = ++count;
> > >  	}
> > >  	spin_unlock_irqrestore(&io_tlb_lock, flags);
> > > --
> > > 1.7.9.5
> > >

RE: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize configurable as flexible requirement about SW-IOMMU.

[Wang, Xiaoming]

Dear Wilk:

> -----Original Message-----
> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@oracle.com]
> Sent: Saturday, February 7, 2015 2:12 AM
> To: Wang, Xiaoming
> Cc: ralf@linux-mips.org; boris.ostrovsky@oracle.com;
> david.vrabel@citrix.com; linux-mips@linux-mips.org; linux-
> kernel@vger.kernel.org; xen-devel@lists.xenproject.org; akpm@linux-
> foundation.org; linux@horizon.com; lauraa@codeaurora.org;
> heiko.carstens@de.ibm.com; d.kasatkin@samsung.com;
> takahiro.akashi@linaro.org; chris@chris-wilson.co.uk; pebolle@tiscali.nl; Liu,
> Chuansheng; Zhang, Dongxing
> Subject: Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize
> configurable as flexible requirement about SW-IOMMU.
> 
> On Fri, Feb 06, 2015 at 12:10:15AM +0000, Wang, Xiaoming wrote:
> >
> >
> > > -----Original Message-----
> > > From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@oracle.com]
> > > Sent: Friday, February 6, 2015 3:33 AM
> > > To: Wang, Xiaoming
> > > Cc: ralf@linux-mips.org; boris.ostrovsky@oracle.com;
> > > david.vrabel@citrix.com; linux-mips@linux-mips.org; linux-
> > > kernel@vger.kernel.org; xen-devel@lists.xenproject.org; akpm@linux-
> > > foundation.org; linux@horizon.com; lauraa@codeaurora.org;
> > > heiko.carstens@de.ibm.com; d.kasatkin@samsung.com;
> > > takahiro.akashi@linaro.org; chris@chris-wilson.co.uk;
> > > pebolle@tiscali.nl; Liu, Chuansheng; Zhang, Dongxing
> > > Subject: Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize
> > > configurable as flexible requirement about SW-IOMMU.
> > >
> > > On Fri, Feb 06, 2015 at 07:01:14AM +0800, xiaomin1 wrote:
> > > > The maximum of SW-IOMMU is limited to 2^11*128 = 256K.
> > > > While in different platform and different requirements this seems
> improper.
> > > > So modify the IO_TLB_SEGSIZE to io_tlb_segsize as configurable is
> > > > make
> > > sense.
> > >
> > > More details please. What is the issue you are hitting?
> > >
> > Example:
> > If 1M bytes are requied. There has an error like.
> 
> Ok, but even with 1MB size - you only have 64 'slots' (if you allocate an 64MB
> buffer). And the other 'slots' can be fragmented so you might still not have
> enough 1MB chunks available.
> 
> Do you have some thoughts on how that would be addressed?
> 
Yes, 
If IO_TLB_SEGSIZE is 128 the slabs is 32K/128 = 256
While IO_TLB_SEGSIZE is 512 the slabs is 32K/512 =64 (for 1M).
So it is dilemma between slabs and segsize.
I have a thought how about modifying the IO_TLB_DEFAULT_SIZE to 
io_tlb_default_size  configurable too?
Because of the multivariate requirement.

> > [   31.474769] dwc3_otg 0000:00:16.0:
> dwc3_intel_byt_notify_charger_type(): dwc3_intel_byt_notify_charger_type:
> invalid SDP current!
> > [   31.554077] android_work: sent uevent USB_STATE=CONNECTED
> > [   31.564244] android_usb gadget: high-speed config #1: android
> > [   31.571468] android_work: sent uevent USB_STATE=CONFIGURED
> > [   31.942738] DMA: Out of SW-IOMMU space for 1048576 bytes at device
> gadget
> > [   31.950345] Kernel panic - not syncing: DMA: Random memory could be
> DMA written
> > [   31.950345]
> > [   31.960170] CPU: 1 PID: 172 Comm: droidboot Tainted: G        W
> 3.10.20-x86_64_byt-g1077f87 #2
> > [   31.970086] Hardware name: Intel Corp. VALLEYVIEW C0
> PLATFORM/BYT-T FFD8, BIOS BLADE_21.X64.0004.R14.1412311144
> FFD8_X64_R_2014_12_31_1151 12/31/2014
> > [   31.985053]  0000000000100000 ffff880136c2fc98 ffffffff82967d45
> ffff880136c2fd10
> > [   31.993327]  ffffffff82961761 0000000000000008 ffff880136c2fd20
> ffff880136c2fcc0
> > [   32.001590]  ffffffff829618fb 0000000000000002 ffffffff820aeff9
> 0000000000008d8c
> > [   32.009871] Call Trace:
> > [   32.012610]  [<ffffffff82967d45>] dump_stack+0x19/0x1b
> > [   32.018353]  [<ffffffff82961761>] panic+0xc8/0x1d6
> > [   32.023707]  [<ffffffff829618fb>] ? printk+0x55/0x57
> > [   32.029258]  [<ffffffff820aeff9>] ? console_unlock+0x1f9/0x460
> > [   32.035772]  [<ffffffff82347cbe>] swiotlb_map_page+0x12e/0x140
> > [   32.042283]  [<ffffffff82599d4d>]
> usb_gadget_map_request+0x16d/0x220
> > [   32.049387]  [<ffffffff8255ce89>] dwc3_gadget_ep_queue+0x229/0x460
> > [   32.056297]  [<ffffffff825b4624>] ffs_epfile_io.isra.96+0x3e4/0x520
> > [   32.063296]  [<ffffffff820e438d>] ? get_parent_ip+0xd/0x50
> > [   32.069427]  [<ffffffff82975a61>] ? sub_preempt_count+0x71/0x100
> > [   32.076142]  [<ffffffff825b47b8>] ffs_epfile_read+0x28/0x30
> > [   32.082370]  [<ffffffff821b6b8c>] vfs_read+0x9c/0x170
> > [   32.088014]  [<ffffffff821b765d>] SyS_read+0x4d/0xa0
> > [   32.093562]  [<ffffffff8297b179>] ia32_do_call+0x13/0x13
> > > >
> > > > Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com>
> > > > Signed-off-by: Zhang Dongxing <dongxing.zhang@intel.com>
> > > > Signed-off-by: xiaomin1 <xiaoming.wang@intel.com>
> > > > ---
> > > >  arch/mips/cavium-octeon/dma-octeon.c |    2 +-
> > > >  arch/mips/netlogic/common/nlm-dma.c  |    2 +-
> > > >  drivers/xen/swiotlb-xen.c            |    6 +++---
> > > >  include/linux/swiotlb.h              |    8 +------
> > > >  lib/swiotlb.c                        |   39 ++++++++++++++++++++++++----------
> > > >  5 files changed, 34 insertions(+), 23 deletions(-)
> > > >
> > > > diff --git a/arch/mips/cavium-octeon/dma-octeon.c
> > > > b/arch/mips/cavium-octeon/dma-octeon.c
> > > > index 3778655..a521af6 100644
> > > > --- a/arch/mips/cavium-octeon/dma-octeon.c
> > > > +++ b/arch/mips/cavium-octeon/dma-octeon.c
> > > > @@ -312,7 +312,7 @@ void __init plat_swiotlb_setup(void)
> > > >  		swiotlbsize = 64 * (1<<20);
> > > >  #endif
> > > >  	swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> > > > -	swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> > > > +	swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
> > > >  	swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
> > > >
> > > >  	octeon_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> > > > diff --git a/arch/mips/netlogic/common/nlm-dma.c
> > > > b/arch/mips/netlogic/common/nlm-dma.c
> > > > index f3d4ae8..eeffa8f 100644
> > > > --- a/arch/mips/netlogic/common/nlm-dma.c
> > > > +++ b/arch/mips/netlogic/common/nlm-dma.c
> > > > @@ -99,7 +99,7 @@ void __init plat_swiotlb_setup(void)
> > > >
> > > >  	swiotlbsize = 1 << 20; /* 1 MB for now */
> > > >  	swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> > > > -	swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> > > > +	swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
> > > >  	swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
> > > >
> > > >  	nlm_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> > > > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> > > > index 810ad41..3b3e9fe 100644
> > > > --- a/drivers/xen/swiotlb-xen.c
> > > > +++ b/drivers/xen/swiotlb-xen.c
> > > > @@ -164,11 +164,11 @@ xen_swiotlb_fixup(void *buf, size_t size,
> > > unsigned long nslabs)
> > > >  	dma_addr_t dma_handle;
> > > >  	phys_addr_t p = virt_to_phys(buf);
> > > >
> > > > -	dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) +
> > > PAGE_SHIFT;
> > > > +	dma_bits = get_order(io_tlb_segsize << IO_TLB_SHIFT) +
> > > > +PAGE_SHIFT;
> > > >
> > > >  	i = 0;
> > > >  	do {
> > > > -		int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE);
> > > > +		int slabs = min(nslabs - i, (unsigned long)io_tlb_segsize);
> > > >
> > > >  		do {
> > > >  			rc = xen_create_contiguous_region( @@ -187,7
> > > +187,7 @@ static
> > > > unsigned long xen_set_nslabs(unsigned long nr_tbl)  {
> > > >  	if (!nr_tbl) {
> > > >  		xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
> > > > -		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs,
> > > IO_TLB_SEGSIZE);
> > > > +		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, io_tlb_segsize);
> > > >  	} else
> > > >  		xen_io_tlb_nslabs = nr_tbl;
> > > >
> > > > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
> > > > index e7a018e..13506db 100644
> > > > --- a/include/linux/swiotlb.h
> > > > +++ b/include/linux/swiotlb.h
> > > > @@ -8,13 +8,7 @@ struct dma_attrs;  struct scatterlist;
> > > >
> > > >  extern int swiotlb_force;
> > > > -
> > > > -/*
> > > > - * Maximum allowable number of contiguous slabs to map,
> > > > - * must be a power of 2.  What is the appropriate value ?
> > > > - * The complexity of {map,unmap}_single is linearly dependent on
> > > > this
> > > value.
> > > > - */
> > > > -#define IO_TLB_SEGSIZE	128
> > > > +extern int io_tlb_segsize;
> > > >
> > > >  /*
> > > >   * log of the size of each IO TLB slab.  The number of slabs is
> > > > command line diff --git a/lib/swiotlb.c b/lib/swiotlb.c index
> > > > 4abda07..50c415a 100644
> > > > --- a/lib/swiotlb.c
> > > > +++ b/lib/swiotlb.c
> > > > @@ -56,6 +56,15 @@
> > > >  int swiotlb_force;
> > > >
> > > >  /*
> > > > + * Maximum allowable number of contiguous slabs to map,
> > > > + * must be a power of 2.  What is the appropriate value ?
> > > > + * define io_tlb_segsize as a parameter
> > > > + * which can be changed dynamically in config file for special usage.
> > > > + * The complexity of {map,unmap}_single is linearly dependent on
> > > > + this
> > > value.
> > > > + */
> > > > +int io_tlb_segsize = 128;
> > > > +
> > > > +/*
> > > >   * Used to do a quick range check in swiotlb_tbl_unmap_single and
> > > >   * swiotlb_tbl_sync_single_*, to see if the memory was in fact
> > > > allocated by
> > > this
> > > >   * API.
> > > > @@ -97,12 +106,20 @@ static DEFINE_SPINLOCK(io_tlb_lock);  static
> > > > int late_alloc;
> > > >
> > > >  static int __init
> > > > +setup_io_tlb_segsize(char *str)
> > > > +{
> > > > +	get_option(&str, &io_tlb_segsize);
> > > > +	return 0;
> > > > +}
> > > > +__setup("io_tlb_segsize=", setup_io_tlb_segsize);
> > > > +
> > > > +static int __init
> > > >  setup_io_tlb_npages(char *str)
> > > >  {
> > > >  	if (isdigit(*str)) {
> > > >  		io_tlb_nslabs = simple_strtoul(str, &str, 0);
> > > > -		/* avoid tail segment of size < IO_TLB_SEGSIZE */
> > > > -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > > > +		/* avoid tail segment of size < io_tlb_segsize */
> > > > +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> > > >  	}
> > > >  	if (*str == ',')
> > > >  		++str;
> > > > @@ -183,7 +200,7 @@ int __init swiotlb_init_with_tbl(char *tlb,
> > > > unsigned long nslabs, int verbose)
> > > >
> > > >  	/*
> > > >  	 * Allocate and initialize the free list array.  This array is used
> > > > -	 * to find contiguous free memory regions of size up to
> > > IO_TLB_SEGSIZE
> > > > +	 * to find contiguous free memory regions of size up to
> > > > +io_tlb_segsize
> > > >  	 * between io_tlb_start and io_tlb_end.
> > > >  	 */
> > > >  	io_tlb_list = memblock_virt_alloc( @@ -193,7 +210,7 @@ int
> > > > __init swiotlb_init_with_tbl(char *tlb, unsigned
> > > long nslabs, int verbose)
> > > >  				PAGE_ALIGN(io_tlb_nslabs *
> > > sizeof(phys_addr_t)),
> > > >  				PAGE_SIZE);
> > > >  	for (i = 0; i < io_tlb_nslabs; i++) {
> > > > -		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
> > > > +		io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
> > > >  		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> > > >  	}
> > > >  	io_tlb_index = 0;
> > > > @@ -217,7 +234,7 @@ swiotlb_init(int verbose)
> > > >
> > > >  	if (!io_tlb_nslabs) {
> > > >  		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > > > -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > > > +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> > > >  	}
> > > >
> > > >  	bytes = io_tlb_nslabs << IO_TLB_SHIFT; @@ -249,7 +266,7 @@
> > > > swiotlb_late_init_with_default_size(size_t default_size)
> > > >
> > > >  	if (!io_tlb_nslabs) {
> > > >  		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > > > -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > > > +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> > > >  	}
> > > >
> > > >  	/*
> > > > @@ -308,7 +325,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned
> > > > long nslabs)
> > > >
> > > >  	/*
> > > >  	 * Allocate and initialize the free list array.  This array is used
> > > > -	 * to find contiguous free memory regions of size up to
> > > IO_TLB_SEGSIZE
> > > > +	 * to find contiguous free memory regions of size up to
> > > > +io_tlb_segsize
> > > >  	 * between io_tlb_start and io_tlb_end.
> > > >  	 */
> > > >  	io_tlb_list = (unsigned int *)__get_free_pages(GFP_KERNEL, @@ -
> > > 324,7
> > > > +341,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long
> > > > +nslabs)
> > > >  		goto cleanup4;
> > > >
> > > >  	for (i = 0; i < io_tlb_nslabs; i++) {
> > > > -		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
> > > > +		io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
> > > >  		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> > > >  	}
> > > >  	io_tlb_index = 0;
> > > > @@ -493,7 +510,7 @@ phys_addr_t swiotlb_tbl_map_single(struct
> > > > device *hwdev,
> > > >
> > > >  			for (i = index; i < (int) (index + nslots); i++)
> > > >  				io_tlb_list[i] = 0;
> > > > -			for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) !=
> > > IO_TLB_SEGSIZE - 1) && io_tlb_list[i]; i--)
> > > > +			for (i = index - 1; (OFFSET(i, io_tlb_segsize) !=
> > > io_tlb_segsize -
> > > > +1) && io_tlb_list[i]; i--)
> > > >  				io_tlb_list[i] = ++count;
> > > >  			tlb_addr = io_tlb_start + (index << IO_TLB_SHIFT);
> > > >
> > > > @@ -571,7 +588,7 @@ void swiotlb_tbl_unmap_single(struct device
> > > *hwdev, phys_addr_t tlb_addr,
> > > >  	 */
> > > >  	spin_lock_irqsave(&io_tlb_lock, flags);
> > > >  	{
> > > > -		count = ((index + nslots) < ALIGN(index + 1, IO_TLB_SEGSIZE) ?
> > > > +		count = ((index + nslots) < ALIGN(index + 1, io_tlb_segsize) ?
> > > >  			 io_tlb_list[index + nslots] : 0);
> > > >  		/*
> > > >  		 * Step 1: return the slots to the free list, merging the @@ -
> > > 585,7
> > > > +602,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev,
> > > phys_addr_t tlb_addr,
> > > >  		 * Step 2: merge the returned slots with the preceding slots,
> > > >  		 * if available (non zero)
> > > >  		 */
> > > > -		for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) !=
> > > IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
> > > > +		for (i = index - 1; (OFFSET(i, io_tlb_segsize) !=
> > > > +io_tlb_segsize
> > > > +-1) && io_tlb_list[i]; i--)
> > > >  			io_tlb_list[i] = ++count;
> > > >  	}
> > > >  	spin_unlock_irqrestore(&io_tlb_lock, flags);
> > > > --
> > > > 1.7.9.5
> > > >

Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize configurable as flexible requirement about SW-IOMMU.

[Konrad Rzeszutek Wilk]

On Mon, Feb 09, 2015 at 02:13:30AM +0000, Wang, Xiaoming wrote:
> Dear Wilk:
> 
> > -----Original Message-----
> > From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@oracle.com]
> > Sent: Saturday, February 7, 2015 2:12 AM
> > To: Wang, Xiaoming
> > Cc: ralf@linux-mips.org; boris.ostrovsky@oracle.com;
> > david.vrabel@citrix.com; linux-mips@linux-mips.org; linux-
> > kernel@vger.kernel.org; xen-devel@lists.xenproject.org; akpm@linux-
> > foundation.org; linux@horizon.com; lauraa@codeaurora.org;
> > heiko.carstens@de.ibm.com; d.kasatkin@samsung.com;
> > takahiro.akashi@linaro.org; chris@chris-wilson.co.uk; pebolle@tiscali.nl; Liu,
> > Chuansheng; Zhang, Dongxing
> > Subject: Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize
> > configurable as flexible requirement about SW-IOMMU.
> > 
> > On Fri, Feb 06, 2015 at 12:10:15AM +0000, Wang, Xiaoming wrote:
> > >
> > >
> > > > -----Original Message-----
> > > > From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@oracle.com]
> > > > Sent: Friday, February 6, 2015 3:33 AM
> > > > To: Wang, Xiaoming
> > > > Cc: ralf@linux-mips.org; boris.ostrovsky@oracle.com;
> > > > david.vrabel@citrix.com; linux-mips@linux-mips.org; linux-
> > > > kernel@vger.kernel.org; xen-devel@lists.xenproject.org; akpm@linux-
> > > > foundation.org; linux@horizon.com; lauraa@codeaurora.org;
> > > > heiko.carstens@de.ibm.com; d.kasatkin@samsung.com;
> > > > takahiro.akashi@linaro.org; chris@chris-wilson.co.uk;
> > > > pebolle@tiscali.nl; Liu, Chuansheng; Zhang, Dongxing
> > > > Subject: Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize
> > > > configurable as flexible requirement about SW-IOMMU.
> > > >
> > > > On Fri, Feb 06, 2015 at 07:01:14AM +0800, xiaomin1 wrote:
> > > > > The maximum of SW-IOMMU is limited to 2^11*128 = 256K.
> > > > > While in different platform and different requirements this seems
> > improper.
> > > > > So modify the IO_TLB_SEGSIZE to io_tlb_segsize as configurable is
> > > > > make
> > > > sense.
> > > >
> > > > More details please. What is the issue you are hitting?
> > > >
> > > Example:
> > > If 1M bytes are requied. There has an error like.
> > 
> > Ok, but even with 1MB size - you only have 64 'slots' (if you allocate an 64MB
> > buffer). And the other 'slots' can be fragmented so you might still not have
> > enough 1MB chunks available.
> > 
> > Do you have some thoughts on how that would be addressed?
> > 
> Yes, 
> If IO_TLB_SEGSIZE is 128 the slabs is 32K/128 = 256
> While IO_TLB_SEGSIZE is 512 the slabs is 32K/512 =64 (for 1M).
> So it is dilemma between slabs and segsize.

Right.
> I have a thought how about modifying the IO_TLB_DEFAULT_SIZE to 
> io_tlb_default_size  configurable too?

It would seem that 'io_tlb_default_size' should be influenced by
the 'io_tlb_segsize' - as in have some calculation that would
come up with the best value (if there is one?)

> Because of the multivariate requirement.
> 
> > > [   31.474769] dwc3_otg 0000:00:16.0:
> > dwc3_intel_byt_notify_charger_type(): dwc3_intel_byt_notify_charger_type:
> > invalid SDP current!
> > > [   31.554077] android_work: sent uevent USB_STATE=CONNECTED
> > > [   31.564244] android_usb gadget: high-speed config #1: android
> > > [   31.571468] android_work: sent uevent USB_STATE=CONFIGURED
> > > [   31.942738] DMA: Out of SW-IOMMU space for 1048576 bytes at device
> > gadget
> > > [   31.950345] Kernel panic - not syncing: DMA: Random memory could be
> > DMA written
> > > [   31.950345]
> > > [   31.960170] CPU: 1 PID: 172 Comm: droidboot Tainted: G        W
> > 3.10.20-x86_64_byt-g1077f87 #2
> > > [   31.970086] Hardware name: Intel Corp. VALLEYVIEW C0
> > PLATFORM/BYT-T FFD8, BIOS BLADE_21.X64.0004.R14.1412311144
> > FFD8_X64_R_2014_12_31_1151 12/31/2014
> > > [   31.985053]  0000000000100000 ffff880136c2fc98 ffffffff82967d45
> > ffff880136c2fd10
> > > [   31.993327]  ffffffff82961761 0000000000000008 ffff880136c2fd20
> > ffff880136c2fcc0
> > > [   32.001590]  ffffffff829618fb 0000000000000002 ffffffff820aeff9
> > 0000000000008d8c
> > > [   32.009871] Call Trace:
> > > [   32.012610]  [<ffffffff82967d45>] dump_stack+0x19/0x1b
> > > [   32.018353]  [<ffffffff82961761>] panic+0xc8/0x1d6
> > > [   32.023707]  [<ffffffff829618fb>] ? printk+0x55/0x57
> > > [   32.029258]  [<ffffffff820aeff9>] ? console_unlock+0x1f9/0x460
> > > [   32.035772]  [<ffffffff82347cbe>] swiotlb_map_page+0x12e/0x140
> > > [   32.042283]  [<ffffffff82599d4d>]
> > usb_gadget_map_request+0x16d/0x220
> > > [   32.049387]  [<ffffffff8255ce89>] dwc3_gadget_ep_queue+0x229/0x460
> > > [   32.056297]  [<ffffffff825b4624>] ffs_epfile_io.isra.96+0x3e4/0x520
> > > [   32.063296]  [<ffffffff820e438d>] ? get_parent_ip+0xd/0x50
> > > [   32.069427]  [<ffffffff82975a61>] ? sub_preempt_count+0x71/0x100
> > > [   32.076142]  [<ffffffff825b47b8>] ffs_epfile_read+0x28/0x30
> > > [   32.082370]  [<ffffffff821b6b8c>] vfs_read+0x9c/0x170
> > > [   32.088014]  [<ffffffff821b765d>] SyS_read+0x4d/0xa0
> > > [   32.093562]  [<ffffffff8297b179>] ia32_do_call+0x13/0x13
> > > > >
> > > > > Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com>
> > > > > Signed-off-by: Zhang Dongxing <dongxing.zhang@intel.com>
> > > > > Signed-off-by: xiaomin1 <xiaoming.wang@intel.com>
> > > > > ---
> > > > >  arch/mips/cavium-octeon/dma-octeon.c |    2 +-
> > > > >  arch/mips/netlogic/common/nlm-dma.c  |    2 +-
> > > > >  drivers/xen/swiotlb-xen.c            |    6 +++---
> > > > >  include/linux/swiotlb.h              |    8 +------
> > > > >  lib/swiotlb.c                        |   39 ++++++++++++++++++++++++----------
> > > > >  5 files changed, 34 insertions(+), 23 deletions(-)
> > > > >
> > > > > diff --git a/arch/mips/cavium-octeon/dma-octeon.c
> > > > > b/arch/mips/cavium-octeon/dma-octeon.c
> > > > > index 3778655..a521af6 100644
> > > > > --- a/arch/mips/cavium-octeon/dma-octeon.c
> > > > > +++ b/arch/mips/cavium-octeon/dma-octeon.c
> > > > > @@ -312,7 +312,7 @@ void __init plat_swiotlb_setup(void)
> > > > >  		swiotlbsize = 64 * (1<<20);
> > > > >  #endif
> > > > >  	swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> > > > > -	swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> > > > > +	swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
> > > > >  	swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
> > > > >
> > > > >  	octeon_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> > > > > diff --git a/arch/mips/netlogic/common/nlm-dma.c
> > > > > b/arch/mips/netlogic/common/nlm-dma.c
> > > > > index f3d4ae8..eeffa8f 100644
> > > > > --- a/arch/mips/netlogic/common/nlm-dma.c
> > > > > +++ b/arch/mips/netlogic/common/nlm-dma.c
> > > > > @@ -99,7 +99,7 @@ void __init plat_swiotlb_setup(void)
> > > > >
> > > > >  	swiotlbsize = 1 << 20; /* 1 MB for now */
> > > > >  	swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> > > > > -	swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> > > > > +	swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
> > > > >  	swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
> > > > >
> > > > >  	nlm_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> > > > > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> > > > > index 810ad41..3b3e9fe 100644
> > > > > --- a/drivers/xen/swiotlb-xen.c
> > > > > +++ b/drivers/xen/swiotlb-xen.c
> > > > > @@ -164,11 +164,11 @@ xen_swiotlb_fixup(void *buf, size_t size,
> > > > unsigned long nslabs)
> > > > >  	dma_addr_t dma_handle;
> > > > >  	phys_addr_t p = virt_to_phys(buf);
> > > > >
> > > > > -	dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) +
> > > > PAGE_SHIFT;
> > > > > +	dma_bits = get_order(io_tlb_segsize << IO_TLB_SHIFT) +
> > > > > +PAGE_SHIFT;
> > > > >
> > > > >  	i = 0;
> > > > >  	do {
> > > > > -		int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE);
> > > > > +		int slabs = min(nslabs - i, (unsigned long)io_tlb_segsize);
> > > > >
> > > > >  		do {
> > > > >  			rc = xen_create_contiguous_region( @@ -187,7
> > > > +187,7 @@ static
> > > > > unsigned long xen_set_nslabs(unsigned long nr_tbl)  {
> > > > >  	if (!nr_tbl) {
> > > > >  		xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
> > > > > -		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs,
> > > > IO_TLB_SEGSIZE);
> > > > > +		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, io_tlb_segsize);
> > > > >  	} else
> > > > >  		xen_io_tlb_nslabs = nr_tbl;
> > > > >
> > > > > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
> > > > > index e7a018e..13506db 100644
> > > > > --- a/include/linux/swiotlb.h
> > > > > +++ b/include/linux/swiotlb.h
> > > > > @@ -8,13 +8,7 @@ struct dma_attrs;  struct scatterlist;
> > > > >
> > > > >  extern int swiotlb_force;
> > > > > -
> > > > > -/*
> > > > > - * Maximum allowable number of contiguous slabs to map,
> > > > > - * must be a power of 2.  What is the appropriate value ?
> > > > > - * The complexity of {map,unmap}_single is linearly dependent on
> > > > > this
> > > > value.
> > > > > - */
> > > > > -#define IO_TLB_SEGSIZE	128
> > > > > +extern int io_tlb_segsize;
> > > > >
> > > > >  /*
> > > > >   * log of the size of each IO TLB slab.  The number of slabs is
> > > > > command line diff --git a/lib/swiotlb.c b/lib/swiotlb.c index
> > > > > 4abda07..50c415a 100644
> > > > > --- a/lib/swiotlb.c
> > > > > +++ b/lib/swiotlb.c
> > > > > @@ -56,6 +56,15 @@
> > > > >  int swiotlb_force;
> > > > >
> > > > >  /*
> > > > > + * Maximum allowable number of contiguous slabs to map,
> > > > > + * must be a power of 2.  What is the appropriate value ?
> > > > > + * define io_tlb_segsize as a parameter
> > > > > + * which can be changed dynamically in config file for special usage.
> > > > > + * The complexity of {map,unmap}_single is linearly dependent on
> > > > > + this
> > > > value.
> > > > > + */
> > > > > +int io_tlb_segsize = 128;
> > > > > +
> > > > > +/*
> > > > >   * Used to do a quick range check in swiotlb_tbl_unmap_single and
> > > > >   * swiotlb_tbl_sync_single_*, to see if the memory was in fact
> > > > > allocated by
> > > > this
> > > > >   * API.
> > > > > @@ -97,12 +106,20 @@ static DEFINE_SPINLOCK(io_tlb_lock);  static
> > > > > int late_alloc;
> > > > >
> > > > >  static int __init
> > > > > +setup_io_tlb_segsize(char *str)
> > > > > +{
> > > > > +	get_option(&str, &io_tlb_segsize);
> > > > > +	return 0;
> > > > > +}
> > > > > +__setup("io_tlb_segsize=", setup_io_tlb_segsize);
> > > > > +
> > > > > +static int __init
> > > > >  setup_io_tlb_npages(char *str)
> > > > >  {
> > > > >  	if (isdigit(*str)) {
> > > > >  		io_tlb_nslabs = simple_strtoul(str, &str, 0);
> > > > > -		/* avoid tail segment of size < IO_TLB_SEGSIZE */
> > > > > -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > > > > +		/* avoid tail segment of size < io_tlb_segsize */
> > > > > +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> > > > >  	}
> > > > >  	if (*str == ',')
> > > > >  		++str;
> > > > > @@ -183,7 +200,7 @@ int __init swiotlb_init_with_tbl(char *tlb,
> > > > > unsigned long nslabs, int verbose)
> > > > >
> > > > >  	/*
> > > > >  	 * Allocate and initialize the free list array.  This array is used
> > > > > -	 * to find contiguous free memory regions of size up to
> > > > IO_TLB_SEGSIZE
> > > > > +	 * to find contiguous free memory regions of size up to
> > > > > +io_tlb_segsize
> > > > >  	 * between io_tlb_start and io_tlb_end.
> > > > >  	 */
> > > > >  	io_tlb_list = memblock_virt_alloc( @@ -193,7 +210,7 @@ int
> > > > > __init swiotlb_init_with_tbl(char *tlb, unsigned
> > > > long nslabs, int verbose)
> > > > >  				PAGE_ALIGN(io_tlb_nslabs *
> > > > sizeof(phys_addr_t)),
> > > > >  				PAGE_SIZE);
> > > > >  	for (i = 0; i < io_tlb_nslabs; i++) {
> > > > > -		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
> > > > > +		io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
> > > > >  		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> > > > >  	}
> > > > >  	io_tlb_index = 0;
> > > > > @@ -217,7 +234,7 @@ swiotlb_init(int verbose)
> > > > >
> > > > >  	if (!io_tlb_nslabs) {
> > > > >  		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > > > > -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > > > > +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> > > > >  	}
> > > > >
> > > > >  	bytes = io_tlb_nslabs << IO_TLB_SHIFT; @@ -249,7 +266,7 @@
> > > > > swiotlb_late_init_with_default_size(size_t default_size)
> > > > >
> > > > >  	if (!io_tlb_nslabs) {
> > > > >  		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > > > > -		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > > > > +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> > > > >  	}
> > > > >
> > > > >  	/*
> > > > > @@ -308,7 +325,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned
> > > > > long nslabs)
> > > > >
> > > > >  	/*
> > > > >  	 * Allocate and initialize the free list array.  This array is used
> > > > > -	 * to find contiguous free memory regions of size up to
> > > > IO_TLB_SEGSIZE
> > > > > +	 * to find contiguous free memory regions of size up to
> > > > > +io_tlb_segsize
> > > > >  	 * between io_tlb_start and io_tlb_end.
> > > > >  	 */
> > > > >  	io_tlb_list = (unsigned int *)__get_free_pages(GFP_KERNEL, @@ -
> > > > 324,7
> > > > > +341,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long
> > > > > +nslabs)
> > > > >  		goto cleanup4;
> > > > >
> > > > >  	for (i = 0; i < io_tlb_nslabs; i++) {
> > > > > -		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
> > > > > +		io_tlb_list[i] = io_tlb_segsize - OFFSET(i, io_tlb_segsize);
> > > > >  		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> > > > >  	}
> > > > >  	io_tlb_index = 0;
> > > > > @@ -493,7 +510,7 @@ phys_addr_t swiotlb_tbl_map_single(struct
> > > > > device *hwdev,
> > > > >
> > > > >  			for (i = index; i < (int) (index + nslots); i++)
> > > > >  				io_tlb_list[i] = 0;
> > > > > -			for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) !=
> > > > IO_TLB_SEGSIZE - 1) && io_tlb_list[i]; i--)
> > > > > +			for (i = index - 1; (OFFSET(i, io_tlb_segsize) !=
> > > > io_tlb_segsize -
> > > > > +1) && io_tlb_list[i]; i--)
> > > > >  				io_tlb_list[i] = ++count;
> > > > >  			tlb_addr = io_tlb_start + (index << IO_TLB_SHIFT);
> > > > >
> > > > > @@ -571,7 +588,7 @@ void swiotlb_tbl_unmap_single(struct device
> > > > *hwdev, phys_addr_t tlb_addr,
> > > > >  	 */
> > > > >  	spin_lock_irqsave(&io_tlb_lock, flags);
> > > > >  	{
> > > > > -		count = ((index + nslots) < ALIGN(index + 1, IO_TLB_SEGSIZE) ?
> > > > > +		count = ((index + nslots) < ALIGN(index + 1, io_tlb_segsize) ?
> > > > >  			 io_tlb_list[index + nslots] : 0);
> > > > >  		/*
> > > > >  		 * Step 1: return the slots to the free list, merging the @@ -
> > > > 585,7
> > > > > +602,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev,
> > > > phys_addr_t tlb_addr,
> > > > >  		 * Step 2: merge the returned slots with the preceding slots,
> > > > >  		 * if available (non zero)
> > > > >  		 */
> > > > > -		for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) !=
> > > > IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
> > > > > +		for (i = index - 1; (OFFSET(i, io_tlb_segsize) !=
> > > > > +io_tlb_segsize
> > > > > +-1) && io_tlb_list[i]; i--)
> > > > >  			io_tlb_list[i] = ++count;
> > > > >  	}
> > > > >  	spin_unlock_irqrestore(&io_tlb_lock, flags);
> > > > > --
> > > > > 1.7.9.5
> > > > >

RE: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize configurable as flexible requirement about SW-IOMMU.

[Wang, Xiaoming]

Dear Wilk:

> -----Original Message-----
> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@oracle.com]
> Sent: Monday, February 9, 2015 11:36 PM
> To: Wang, Xiaoming
> Cc: ralf@linux-mips.org; boris.ostrovsky@oracle.com;
> david.vrabel@citrix.com; linux-mips@linux-mips.org; linux-
> kernel@vger.kernel.org; xen-devel@lists.xenproject.org; akpm@linux-
> foundation.org; linux@horizon.com; lauraa@codeaurora.org;
> heiko.carstens@de.ibm.com; d.kasatkin@samsung.com;
> takahiro.akashi@linaro.org; chris@chris-wilson.co.uk; pebolle@tiscali.nl; Liu,
> Chuansheng; Zhang, Dongxing
> Subject: Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize
> configurable as flexible requirement about SW-IOMMU.
> 
> On Mon, Feb 09, 2015 at 02:13:30AM +0000, Wang, Xiaoming wrote:
> > Dear Wilk:
> >
> > > -----Original Message-----
> > > From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@oracle.com]
> > > Sent: Saturday, February 7, 2015 2:12 AM
> > > To: Wang, Xiaoming
> > > Cc: ralf@linux-mips.org; boris.ostrovsky@oracle.com;
> > > david.vrabel@citrix.com; linux-mips@linux-mips.org; linux-
> > > kernel@vger.kernel.org; xen-devel@lists.xenproject.org; akpm@linux-
> > > foundation.org; linux@horizon.com; lauraa@codeaurora.org;
> > > heiko.carstens@de.ibm.com; d.kasatkin@samsung.com;
> > > takahiro.akashi@linaro.org; chris@chris-wilson.co.uk;
> > > pebolle@tiscali.nl; Liu, Chuansheng; Zhang, Dongxing
> > > Subject: Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize
> > > configurable as flexible requirement about SW-IOMMU.
> > >
> > > On Fri, Feb 06, 2015 at 12:10:15AM +0000, Wang, Xiaoming wrote:
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@oracle.com]
> > > > > Sent: Friday, February 6, 2015 3:33 AM
> > > > > To: Wang, Xiaoming
> > > > > Cc: ralf@linux-mips.org; boris.ostrovsky@oracle.com;
> > > > > david.vrabel@citrix.com; linux-mips@linux-mips.org; linux-
> > > > > kernel@vger.kernel.org; xen-devel@lists.xenproject.org;
> > > > > akpm@linux- foundation.org; linux@horizon.com;
> > > > > lauraa@codeaurora.org; heiko.carstens@de.ibm.com;
> > > > > d.kasatkin@samsung.com; takahiro.akashi@linaro.org;
> > > > > chris@chris-wilson.co.uk; pebolle@tiscali.nl; Liu, Chuansheng;
> > > > > Zhang, Dongxing
> > > > > Subject: Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize
> > > > > configurable as flexible requirement about SW-IOMMU.
> > > > >
> > > > > On Fri, Feb 06, 2015 at 07:01:14AM +0800, xiaomin1 wrote:
> > > > > > The maximum of SW-IOMMU is limited to 2^11*128 = 256K.
> > > > > > While in different platform and different requirements this
> > > > > > seems
> > > improper.
> > > > > > So modify the IO_TLB_SEGSIZE to io_tlb_segsize as configurable
> > > > > > is make
> > > > > sense.
> > > > >
> > > > > More details please. What is the issue you are hitting?
> > > > >
> > > > Example:
> > > > If 1M bytes are requied. There has an error like.
> > >
> > > Ok, but even with 1MB size - you only have 64 'slots' (if you
> > > allocate an 64MB buffer). And the other 'slots' can be fragmented so
> > > you might still not have enough 1MB chunks available.
> > >
> > > Do you have some thoughts on how that would be addressed?
> > >
> > Yes,
> > If IO_TLB_SEGSIZE is 128 the slabs is 32K/128 = 256 While
> > IO_TLB_SEGSIZE is 512 the slabs is 32K/512 =64 (for 1M).
> > So it is dilemma between slabs and segsize.
> 
> Right.
> > I have a thought how about modifying the IO_TLB_DEFAULT_SIZE to
> > io_tlb_default_size  configurable too?
> 
> It would seem that 'io_tlb_default_size' should be influenced by the
> 'io_tlb_segsize' - as in have some calculation that would come up with the
> best value (if there is one?)
> 
I am not sure if the 256 number of slabs is a standard .
If so there has a fixed calculation between 'io_tlb_default_size' and 'io_tlb_segsize'

But if 'io_tlb_default_size' is limited as 64M in some platforms,
while the max segsize is required as 1M, we have to sacrifice the slabs to meet segsize.
So leaving  'io_tlb_default_size' and 'io_tlb_segsize' independent is better, I think.

> > Because of the multivariate requirement.
> >
> > > > [   31.474769] dwc3_otg 0000:00:16.0:
> > > dwc3_intel_byt_notify_charger_type():
> dwc3_intel_byt_notify_charger_type:
> > > invalid SDP current!
> > > > [   31.554077] android_work: sent uevent USB_STATE=CONNECTED
> > > > [   31.564244] android_usb gadget: high-speed config #1: android
> > > > [   31.571468] android_work: sent uevent USB_STATE=CONFIGURED
> > > > [   31.942738] DMA: Out of SW-IOMMU space for 1048576 bytes at
> device
> > > gadget
> > > > [   31.950345] Kernel panic - not syncing: DMA: Random memory could
> be
> > > DMA written
> > > > [   31.950345]
> > > > [   31.960170] CPU: 1 PID: 172 Comm: droidboot Tainted: G        W
> > > 3.10.20-x86_64_byt-g1077f87 #2
> > > > [   31.970086] Hardware name: Intel Corp. VALLEYVIEW C0
> > > PLATFORM/BYT-T FFD8, BIOS BLADE_21.X64.0004.R14.1412311144
> > > FFD8_X64_R_2014_12_31_1151 12/31/2014
> > > > [   31.985053]  0000000000100000 ffff880136c2fc98 ffffffff82967d45
> > > ffff880136c2fd10
> > > > [   31.993327]  ffffffff82961761 0000000000000008 ffff880136c2fd20
> > > ffff880136c2fcc0
> > > > [   32.001590]  ffffffff829618fb 0000000000000002 ffffffff820aeff9
> > > 0000000000008d8c
> > > > [   32.009871] Call Trace:
> > > > [   32.012610]  [<ffffffff82967d45>] dump_stack+0x19/0x1b
> > > > [   32.018353]  [<ffffffff82961761>] panic+0xc8/0x1d6
> > > > [   32.023707]  [<ffffffff829618fb>] ? printk+0x55/0x57
> > > > [   32.029258]  [<ffffffff820aeff9>] ? console_unlock+0x1f9/0x460
> > > > [   32.035772]  [<ffffffff82347cbe>] swiotlb_map_page+0x12e/0x140
> > > > [   32.042283]  [<ffffffff82599d4d>]
> > > usb_gadget_map_request+0x16d/0x220
> > > > [   32.049387]  [<ffffffff8255ce89>]
> dwc3_gadget_ep_queue+0x229/0x460
> > > > [   32.056297]  [<ffffffff825b4624>] ffs_epfile_io.isra.96+0x3e4/0x520
> > > > [   32.063296]  [<ffffffff820e438d>] ? get_parent_ip+0xd/0x50
> > > > [   32.069427]  [<ffffffff82975a61>] ? sub_preempt_count+0x71/0x100
> > > > [   32.076142]  [<ffffffff825b47b8>] ffs_epfile_read+0x28/0x30
> > > > [   32.082370]  [<ffffffff821b6b8c>] vfs_read+0x9c/0x170
> > > > [   32.088014]  [<ffffffff821b765d>] SyS_read+0x4d/0xa0
> > > > [   32.093562]  [<ffffffff8297b179>] ia32_do_call+0x13/0x13
> > > > > >
> > > > > > Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com>
> > > > > > Signed-off-by: Zhang Dongxing <dongxing.zhang@intel.com>
> > > > > > Signed-off-by: xiaomin1 <xiaoming.wang@intel.com>
> > > > > > ---
> > > > > >  arch/mips/cavium-octeon/dma-octeon.c |    2 +-
> > > > > >  arch/mips/netlogic/common/nlm-dma.c  |    2 +-
> > > > > >  drivers/xen/swiotlb-xen.c            |    6 +++---
> > > > > >  include/linux/swiotlb.h              |    8 +------
> > > > > >  lib/swiotlb.c                        |   39 ++++++++++++++++++++++++--------
> --
> > > > > >  5 files changed, 34 insertions(+), 23 deletions(-)
> > > > > >
> > > > > > diff --git a/arch/mips/cavium-octeon/dma-octeon.c
> > > > > > b/arch/mips/cavium-octeon/dma-octeon.c
> > > > > > index 3778655..a521af6 100644
> > > > > > --- a/arch/mips/cavium-octeon/dma-octeon.c
> > > > > > +++ b/arch/mips/cavium-octeon/dma-octeon.c
> > > > > > @@ -312,7 +312,7 @@ void __init plat_swiotlb_setup(void)
> > > > > >  		swiotlbsize = 64 * (1<<20);  #endif
> > > > > >  	swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> > > > > > -	swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> > > > > > +	swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
> > > > > >  	swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
> > > > > >
> > > > > >  	octeon_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> > > > > > diff --git a/arch/mips/netlogic/common/nlm-dma.c
> > > > > > b/arch/mips/netlogic/common/nlm-dma.c
> > > > > > index f3d4ae8..eeffa8f 100644
> > > > > > --- a/arch/mips/netlogic/common/nlm-dma.c
> > > > > > +++ b/arch/mips/netlogic/common/nlm-dma.c
> > > > > > @@ -99,7 +99,7 @@ void __init plat_swiotlb_setup(void)
> > > > > >
> > > > > >  	swiotlbsize = 1 << 20; /* 1 MB for now */
> > > > > >  	swiotlb_nslabs = swiotlbsize >> IO_TLB_SHIFT;
> > > > > > -	swiotlb_nslabs = ALIGN(swiotlb_nslabs, IO_TLB_SEGSIZE);
> > > > > > +	swiotlb_nslabs = ALIGN(swiotlb_nslabs, io_tlb_segsize);
> > > > > >  	swiotlbsize = swiotlb_nslabs << IO_TLB_SHIFT;
> > > > > >
> > > > > >  	nlm_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
> > > > > > diff --git a/drivers/xen/swiotlb-xen.c
> > > > > > b/drivers/xen/swiotlb-xen.c index 810ad41..3b3e9fe 100644
> > > > > > --- a/drivers/xen/swiotlb-xen.c
> > > > > > +++ b/drivers/xen/swiotlb-xen.c
> > > > > > @@ -164,11 +164,11 @@ xen_swiotlb_fixup(void *buf, size_t
> > > > > > size,
> > > > > unsigned long nslabs)
> > > > > >  	dma_addr_t dma_handle;
> > > > > >  	phys_addr_t p = virt_to_phys(buf);
> > > > > >
> > > > > > -	dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) +
> > > > > PAGE_SHIFT;
> > > > > > +	dma_bits = get_order(io_tlb_segsize << IO_TLB_SHIFT) +
> > > > > > +PAGE_SHIFT;
> > > > > >
> > > > > >  	i = 0;
> > > > > >  	do {
> > > > > > -		int slabs = min(nslabs - i, (unsigned
> long)IO_TLB_SEGSIZE);
> > > > > > +		int slabs = min(nslabs - i, (unsigned
> long)io_tlb_segsize);
> > > > > >
> > > > > >  		do {
> > > > > >  			rc = xen_create_contiguous_region( @@ -
> 187,7
> > > > > +187,7 @@ static
> > > > > > unsigned long xen_set_nslabs(unsigned long nr_tbl)  {
> > > > > >  	if (!nr_tbl) {
> > > > > >  		xen_io_tlb_nslabs = (64 * 1024 * 1024 >>
> IO_TLB_SHIFT);
> > > > > > -		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs,
> > > > > IO_TLB_SEGSIZE);
> > > > > > +		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs,
> > > > > > +io_tlb_segsize);
> > > > > >  	} else
> > > > > >  		xen_io_tlb_nslabs = nr_tbl;
> > > > > >
> > > > > > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
> > > > > > index e7a018e..13506db 100644
> > > > > > --- a/include/linux/swiotlb.h
> > > > > > +++ b/include/linux/swiotlb.h
> > > > > > @@ -8,13 +8,7 @@ struct dma_attrs;  struct scatterlist;
> > > > > >
> > > > > >  extern int swiotlb_force;
> > > > > > -
> > > > > > -/*
> > > > > > - * Maximum allowable number of contiguous slabs to map,
> > > > > > - * must be a power of 2.  What is the appropriate value ?
> > > > > > - * The complexity of {map,unmap}_single is linearly dependent
> > > > > > on this
> > > > > value.
> > > > > > - */
> > > > > > -#define IO_TLB_SEGSIZE	128
> > > > > > +extern int io_tlb_segsize;
> > > > > >
> > > > > >  /*
> > > > > >   * log of the size of each IO TLB slab.  The number of slabs
> > > > > > is command line diff --git a/lib/swiotlb.c b/lib/swiotlb.c
> > > > > > index 4abda07..50c415a 100644
> > > > > > --- a/lib/swiotlb.c
> > > > > > +++ b/lib/swiotlb.c
> > > > > > @@ -56,6 +56,15 @@
> > > > > >  int swiotlb_force;
> > > > > >
> > > > > >  /*
> > > > > > + * Maximum allowable number of contiguous slabs to map,
> > > > > > + * must be a power of 2.  What is the appropriate value ?
> > > > > > + * define io_tlb_segsize as a parameter
> > > > > > + * which can be changed dynamically in config file for special usage.
> > > > > > + * The complexity of {map,unmap}_single is linearly dependent
> > > > > > + on this
> > > > > value.
> > > > > > + */
> > > > > > +int io_tlb_segsize = 128;
> > > > > > +
> > > > > > +/*
> > > > > >   * Used to do a quick range check in swiotlb_tbl_unmap_single and
> > > > > >   * swiotlb_tbl_sync_single_*, to see if the memory was in
> > > > > > fact allocated by
> > > > > this
> > > > > >   * API.
> > > > > > @@ -97,12 +106,20 @@ static DEFINE_SPINLOCK(io_tlb_lock);
> > > > > > static int late_alloc;
> > > > > >
> > > > > >  static int __init
> > > > > > +setup_io_tlb_segsize(char *str) {
> > > > > > +	get_option(&str, &io_tlb_segsize);
> > > > > > +	return 0;
> > > > > > +}
> > > > > > +__setup("io_tlb_segsize=", setup_io_tlb_segsize);
> > > > > > +
> > > > > > +static int __init
> > > > > >  setup_io_tlb_npages(char *str)  {
> > > > > >  	if (isdigit(*str)) {
> > > > > >  		io_tlb_nslabs = simple_strtoul(str, &str, 0);
> > > > > > -		/* avoid tail segment of size < IO_TLB_SEGSIZE */
> > > > > > -		io_tlb_nslabs = ALIGN(io_tlb_nslabs,
> IO_TLB_SEGSIZE);
> > > > > > +		/* avoid tail segment of size < io_tlb_segsize */
> > > > > > +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> > > > > >  	}
> > > > > >  	if (*str == ',')
> > > > > >  		++str;
> > > > > > @@ -183,7 +200,7 @@ int __init swiotlb_init_with_tbl(char
> > > > > > *tlb, unsigned long nslabs, int verbose)
> > > > > >
> > > > > >  	/*
> > > > > >  	 * Allocate and initialize the free list array.  This array is used
> > > > > > -	 * to find contiguous free memory regions of size up to
> > > > > IO_TLB_SEGSIZE
> > > > > > +	 * to find contiguous free memory regions of size up to
> > > > > > +io_tlb_segsize
> > > > > >  	 * between io_tlb_start and io_tlb_end.
> > > > > >  	 */
> > > > > >  	io_tlb_list = memblock_virt_alloc( @@ -193,7 +210,7 @@ int
> > > > > > __init swiotlb_init_with_tbl(char *tlb, unsigned
> > > > > long nslabs, int verbose)
> > > > > >  				PAGE_ALIGN(io_tlb_nslabs *
> > > > > sizeof(phys_addr_t)),
> > > > > >  				PAGE_SIZE);
> > > > > >  	for (i = 0; i < io_tlb_nslabs; i++) {
> > > > > > -		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i,
> IO_TLB_SEGSIZE);
> > > > > > +		io_tlb_list[i] = io_tlb_segsize - OFFSET(i,
> > > > > > +io_tlb_segsize);
> > > > > >  		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> > > > > >  	}
> > > > > >  	io_tlb_index = 0;
> > > > > > @@ -217,7 +234,7 @@ swiotlb_init(int verbose)
> > > > > >
> > > > > >  	if (!io_tlb_nslabs) {
> > > > > >  		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > > > > > -		io_tlb_nslabs = ALIGN(io_tlb_nslabs,
> IO_TLB_SEGSIZE);
> > > > > > +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> > > > > >  	}
> > > > > >
> > > > > >  	bytes = io_tlb_nslabs << IO_TLB_SHIFT; @@ -249,7 +266,7
> @@
> > > > > > swiotlb_late_init_with_default_size(size_t default_size)
> > > > > >
> > > > > >  	if (!io_tlb_nslabs) {
> > > > > >  		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > > > > > -		io_tlb_nslabs = ALIGN(io_tlb_nslabs,
> IO_TLB_SEGSIZE);
> > > > > > +		io_tlb_nslabs = ALIGN(io_tlb_nslabs, io_tlb_segsize);
> > > > > >  	}
> > > > > >
> > > > > >  	/*
> > > > > > @@ -308,7 +325,7 @@ swiotlb_late_init_with_tbl(char *tlb,
> > > > > > unsigned long nslabs)
> > > > > >
> > > > > >  	/*
> > > > > >  	 * Allocate and initialize the free list array.  This array is used
> > > > > > -	 * to find contiguous free memory regions of size up to
> > > > > IO_TLB_SEGSIZE
> > > > > > +	 * to find contiguous free memory regions of size up to
> > > > > > +io_tlb_segsize
> > > > > >  	 * between io_tlb_start and io_tlb_end.
> > > > > >  	 */
> > > > > >  	io_tlb_list = (unsigned int *)__get_free_pages(GFP_KERNEL,
> > > > > > @@ -
> > > > > 324,7
> > > > > > +341,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long
> > > > > > +nslabs)
> > > > > >  		goto cleanup4;
> > > > > >
> > > > > >  	for (i = 0; i < io_tlb_nslabs; i++) {
> > > > > > -		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i,
> IO_TLB_SEGSIZE);
> > > > > > +		io_tlb_list[i] = io_tlb_segsize - OFFSET(i,
> > > > > > +io_tlb_segsize);
> > > > > >  		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> > > > > >  	}
> > > > > >  	io_tlb_index = 0;
> > > > > > @@ -493,7 +510,7 @@ phys_addr_t swiotlb_tbl_map_single(struct
> > > > > > device *hwdev,
> > > > > >
> > > > > >  			for (i = index; i < (int) (index + nslots); i++)
> > > > > >  				io_tlb_list[i] = 0;
> > > > > > -			for (i = index - 1; (OFFSET(i,
> IO_TLB_SEGSIZE) !=
> > > > > IO_TLB_SEGSIZE - 1) && io_tlb_list[i]; i--)
> > > > > > +			for (i = index - 1; (OFFSET(i, io_tlb_segsize) !=
> > > > > io_tlb_segsize -
> > > > > > +1) && io_tlb_list[i]; i--)
> > > > > >  				io_tlb_list[i] = ++count;
> > > > > >  			tlb_addr = io_tlb_start + (index <<
> IO_TLB_SHIFT);
> > > > > >
> > > > > > @@ -571,7 +588,7 @@ void swiotlb_tbl_unmap_single(struct
> > > > > > device
> > > > > *hwdev, phys_addr_t tlb_addr,
> > > > > >  	 */
> > > > > >  	spin_lock_irqsave(&io_tlb_lock, flags);
> > > > > >  	{
> > > > > > -		count = ((index + nslots) < ALIGN(index + 1,
> IO_TLB_SEGSIZE) ?
> > > > > > +		count = ((index + nslots) < ALIGN(index + 1,
> io_tlb_segsize) ?
> > > > > >  			 io_tlb_list[index + nslots] : 0);
> > > > > >  		/*
> > > > > >  		 * Step 1: return the slots to the free list, merging the
> > > > > > @@ -
> > > > > 585,7
> > > > > > +602,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev,
> > > > > phys_addr_t tlb_addr,
> > > > > >  		 * Step 2: merge the returned slots with the
> preceding slots,
> > > > > >  		 * if available (non zero)
> > > > > >  		 */
> > > > > > -		for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) !=
> > > > > IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
> > > > > > +		for (i = index - 1; (OFFSET(i, io_tlb_segsize) !=
> > > > > > +io_tlb_segsize
> > > > > > +-1) && io_tlb_list[i]; i--)
> > > > > >  			io_tlb_list[i] = ++count;
> > > > > >  	}
> > > > > >  	spin_unlock_irqrestore(&io_tlb_lock, flags);
> > > > > > --
> > > > > > 1.7.9.5
> > > > > >

Re: [Xen-devel] [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize configurable as flexible requirement about SW-IOMMU.

[David Vrabel]

On 06/02/15 00:10, Wang, Xiaoming wrote:
> 
> 
>> -----Original Message-----
>> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@oracle.com]
>> Sent: Friday, February 6, 2015 3:33 AM
>> To: Wang, Xiaoming
>> Cc: ralf@linux-mips.org; boris.ostrovsky@oracle.com;
>> david.vrabel@citrix.com; linux-mips@linux-mips.org; linux-
>> kernel@vger.kernel.org; xen-devel@lists.xenproject.org; akpm@linux-
>> foundation.org; linux@horizon.com; lauraa@codeaurora.org;
>> heiko.carstens@de.ibm.com; d.kasatkin@samsung.com;
>> takahiro.akashi@linaro.org; chris@chris-wilson.co.uk; pebolle@tiscali.nl; Liu,
>> Chuansheng; Zhang, Dongxing
>> Subject: Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize
>> configurable as flexible requirement about SW-IOMMU.
>>
>> On Fri, Feb 06, 2015 at 07:01:14AM +0800, xiaomin1 wrote:
>>> The maximum of SW-IOMMU is limited to 2^11*128 = 256K.
>>> While in different platform and different requirements this seems improper.
>>> So modify the IO_TLB_SEGSIZE to io_tlb_segsize as configurable is make
>> sense.
>>
>> More details please. What is the issue you are hitting?
>>
> Example:
> If 1M bytes are requied. There has an error like.

Instead of allowing the bouncing of such large buffers, could the gadget
driver be modified to submit the buffers to the hardware in smaller chunks?

David

RE: [Xen-devel] [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize configurable as flexible requirement about SW-IOMMU.

[Wang, Xiaoming]

Dear David

> -----Original Message-----
> From: David Vrabel [mailto:david.vrabel@citrix.com]
> Sent: Tuesday, February 10, 2015 5:46 PM
> To: Wang, Xiaoming; Konrad Rzeszutek Wilk
> Cc: linux-mips@linux-mips.org; pebolle@tiscali.nl; Zhang, Dongxing;
> lauraa@codeaurora.org; d.kasatkin@samsung.com;
> heiko.carstens@de.ibm.com; linux-kernel@vger.kernel.org; ralf@linux-
> mips.org; chris@chris-wilson.co.uk; takahiro.akashi@linaro.org;
> david.vrabel@citrix.com; linux@horizon.com; xen-
> devel@lists.xenproject.org; boris.ostrovsky@oracle.com; Liu, Chuansheng;
> akpm@linux-foundation.org
> Subject: Re: [Xen-devel] [PATCH] modify the IO_TLB_SEGSIZE to
> io_tlb_segsize configurable as flexible requirement about SW-IOMMU.
> 
> On 06/02/15 00:10, Wang, Xiaoming wrote:
> >
> >
> >> -----Original Message-----
> >> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@oracle.com]
> >> Sent: Friday, February 6, 2015 3:33 AM
> >> To: Wang, Xiaoming
> >> Cc: ralf@linux-mips.org; boris.ostrovsky@oracle.com;
> >> david.vrabel@citrix.com; linux-mips@linux-mips.org; linux-
> >> kernel@vger.kernel.org; xen-devel@lists.xenproject.org; akpm@linux-
> >> foundation.org; linux@horizon.com; lauraa@codeaurora.org;
> >> heiko.carstens@de.ibm.com; d.kasatkin@samsung.com;
> >> takahiro.akashi@linaro.org; chris@chris-wilson.co.uk;
> >> pebolle@tiscali.nl; Liu, Chuansheng; Zhang, Dongxing
> >> Subject: Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize
> >> configurable as flexible requirement about SW-IOMMU.
> >>
> >> On Fri, Feb 06, 2015 at 07:01:14AM +0800, xiaomin1 wrote:
> >>> The maximum of SW-IOMMU is limited to 2^11*128 = 256K.
> >>> While in different platform and different requirements this seems
> improper.
> >>> So modify the IO_TLB_SEGSIZE to io_tlb_segsize as configurable is
> >>> make
> >> sense.
> >>
> >> More details please. What is the issue you are hitting?
> >>
> > Example:
> > If 1M bytes are requied. There has an error like.
> 
> Instead of allowing the bouncing of such large buffers, could the gadget
> driver be modified to submit the buffers to the hardware in smaller chunks?
> 
> David

Our target is try to make IO_TLB_SEGSIZE configurable.
Neither 256 bytes  or 1M bytes seems suitable value, I think.
It's better to use the tactics something like
kmem_cache_create  in kmalloc function.
But SW-IOMMU seems more lighter.
So we choose variable rather than function.

Xiaoming.

Re: [Xen-devel] [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize configurable as flexible requirement about SW-IOMMU.

[Konrad Rzeszutek Wilk]

On Wed, Feb 11, 2015 at 08:38:29AM +0000, Wang, Xiaoming wrote:
> Dear David
> 
> > -----Original Message-----
> > From: David Vrabel [mailto:david.vrabel@citrix.com]
> > Sent: Tuesday, February 10, 2015 5:46 PM
> > To: Wang, Xiaoming; Konrad Rzeszutek Wilk
> > Cc: linux-mips@linux-mips.org; pebolle@tiscali.nl; Zhang, Dongxing;
> > lauraa@codeaurora.org; d.kasatkin@samsung.com;
> > heiko.carstens@de.ibm.com; linux-kernel@vger.kernel.org; ralf@linux-
> > mips.org; chris@chris-wilson.co.uk; takahiro.akashi@linaro.org;
> > david.vrabel@citrix.com; linux@horizon.com; xen-
> > devel@lists.xenproject.org; boris.ostrovsky@oracle.com; Liu, Chuansheng;
> > akpm@linux-foundation.org
> > Subject: Re: [Xen-devel] [PATCH] modify the IO_TLB_SEGSIZE to
> > io_tlb_segsize configurable as flexible requirement about SW-IOMMU.
> > 
> > On 06/02/15 00:10, Wang, Xiaoming wrote:
> > >
> > >
> > >> -----Original Message-----
> > >> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@oracle.com]
> > >> Sent: Friday, February 6, 2015 3:33 AM
> > >> To: Wang, Xiaoming
> > >> Cc: ralf@linux-mips.org; boris.ostrovsky@oracle.com;
> > >> david.vrabel@citrix.com; linux-mips@linux-mips.org; linux-
> > >> kernel@vger.kernel.org; xen-devel@lists.xenproject.org; akpm@linux-
> > >> foundation.org; linux@horizon.com; lauraa@codeaurora.org;
> > >> heiko.carstens@de.ibm.com; d.kasatkin@samsung.com;
> > >> takahiro.akashi@linaro.org; chris@chris-wilson.co.uk;
> > >> pebolle@tiscali.nl; Liu, Chuansheng; Zhang, Dongxing
> > >> Subject: Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize
> > >> configurable as flexible requirement about SW-IOMMU.
> > >>
> > >> On Fri, Feb 06, 2015 at 07:01:14AM +0800, xiaomin1 wrote:
> > >>> The maximum of SW-IOMMU is limited to 2^11*128 = 256K.
> > >>> While in different platform and different requirements this seems
> > improper.
> > >>> So modify the IO_TLB_SEGSIZE to io_tlb_segsize as configurable is
> > >>> make
> > >> sense.
> > >>
> > >> More details please. What is the issue you are hitting?
> > >>
> > > Example:
> > > If 1M bytes are requied. There has an error like.
> > 
> > Instead of allowing the bouncing of such large buffers, could the gadget
> > driver be modified to submit the buffers to the hardware in smaller chunks?
> > 
> > David
> 
> Our target is try to make IO_TLB_SEGSIZE configurable.
> Neither 256 bytes  or 1M bytes seems suitable value, I think.
> It's better to use the tactics something like
> kmem_cache_create  in kmalloc function.
> But SW-IOMMU seems more lighter.
> So we choose variable rather than function.

Would it be possible to understand why the gadget needs such
large buffer? That is irrespective of the patchset you are proposing.

In regards to the pathchset - I don't see anything fundamentally
wrong with the patch. What I am afraid is that this fixes the
symptoms instead of the underlaying problem. The problem I think
is that with this large 1MB requests you risk of using the
SWIOTLB bounce buffer which can result in poor performance.

So eventually somebody will have to figure out why the performance
is poor and have a hard time figuring what is wrong - as the
symptoms have been removed.

Hence looking at potentially using an scatter gather mechanism
and chop up the requests in smaller sizes might be an better
option. But I don't know? Perhaps you are more familiar with the
gadget and could tell me why it needs an 1MB size request?


> 
> Xiaoming.

RE: [Xen-devel] [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize configurable as flexible requirement about SW-IOMMU.

[Wang, Xiaoming]

Dear Wilk:

> -----Original Message-----
> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@oracle.com]
> Sent: Thursday, February 12, 2015 4:49 AM
> To: Wang, Xiaoming
> Cc: David Vrabel; linux-mips@linux-mips.org; pebolle@tiscali.nl; Zhang,
> Dongxing; lauraa@codeaurora.org; d.kasatkin@samsung.com;
> heiko.carstens@de.ibm.com; linux-kernel@vger.kernel.org; ralf@linux-
> mips.org; chris@chris-wilson.co.uk; takahiro.akashi@linaro.org;
> linux@horizon.com; xen-devel@lists.xenproject.org;
> boris.ostrovsky@oracle.com; Liu, Chuansheng; akpm@linux-foundation.org
> Subject: Re: [Xen-devel] [PATCH] modify the IO_TLB_SEGSIZE to
> io_tlb_segsize configurable as flexible requirement about SW-IOMMU.
> 
> On Wed, Feb 11, 2015 at 08:38:29AM +0000, Wang, Xiaoming wrote:
> > Dear David
> >
> > > -----Original Message-----
> > > From: David Vrabel [mailto:david.vrabel@citrix.com]
> > > Sent: Tuesday, February 10, 2015 5:46 PM
> > > To: Wang, Xiaoming; Konrad Rzeszutek Wilk
> > > Cc: linux-mips@linux-mips.org; pebolle@tiscali.nl; Zhang, Dongxing;
> > > lauraa@codeaurora.org; d.kasatkin@samsung.com;
> > > heiko.carstens@de.ibm.com; linux-kernel@vger.kernel.org; ralf@linux-
> > > mips.org; chris@chris-wilson.co.uk; takahiro.akashi@linaro.org;
> > > david.vrabel@citrix.com; linux@horizon.com; xen-
> > > devel@lists.xenproject.org; boris.ostrovsky@oracle.com; Liu,
> > > Chuansheng; akpm@linux-foundation.org
> > > Subject: Re: [Xen-devel] [PATCH] modify the IO_TLB_SEGSIZE to
> > > io_tlb_segsize configurable as flexible requirement about SW-IOMMU.
> > >
> > > On 06/02/15 00:10, Wang, Xiaoming wrote:
> > > >
> > > >
> > > >> -----Original Message-----
> > > >> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@oracle.com]
> > > >> Sent: Friday, February 6, 2015 3:33 AM
> > > >> To: Wang, Xiaoming
> > > >> Cc: ralf@linux-mips.org; boris.ostrovsky@oracle.com;
> > > >> david.vrabel@citrix.com; linux-mips@linux-mips.org; linux-
> > > >> kernel@vger.kernel.org; xen-devel@lists.xenproject.org;
> > > >> akpm@linux- foundation.org; linux@horizon.com;
> > > >> lauraa@codeaurora.org; heiko.carstens@de.ibm.com;
> > > >> d.kasatkin@samsung.com; takahiro.akashi@linaro.org;
> > > >> chris@chris-wilson.co.uk; pebolle@tiscali.nl; Liu, Chuansheng;
> > > >> Zhang, Dongxing
> > > >> Subject: Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize
> > > >> configurable as flexible requirement about SW-IOMMU.
> > > >>
> > > >> On Fri, Feb 06, 2015 at 07:01:14AM +0800, xiaomin1 wrote:
> > > >>> The maximum of SW-IOMMU is limited to 2^11*128 = 256K.
> > > >>> While in different platform and different requirements this
> > > >>> seems
> > > improper.
> > > >>> So modify the IO_TLB_SEGSIZE to io_tlb_segsize as configurable
> > > >>> is make
> > > >> sense.
> > > >>
> > > >> More details please. What is the issue you are hitting?
> > > >>
> > > > Example:
> > > > If 1M bytes are requied. There has an error like.
> > >
> > > Instead of allowing the bouncing of such large buffers, could the
> > > gadget driver be modified to submit the buffers to the hardware in
> smaller chunks?
> > >
> > > David
> >
> > Our target is try to make IO_TLB_SEGSIZE configurable.
> > Neither 256 bytes  or 1M bytes seems suitable value, I think.
> > It's better to use the tactics something like kmem_cache_create  in
> > kmalloc function.
> > But SW-IOMMU seems more lighter.
> > So we choose variable rather than function.
> 
> Would it be possible to understand why the gadget needs such large buffer?
> That is irrespective of the patchset you are proposing.
> 
> In regards to the pathchset - I don't see anything fundamentally wrong with
> the patch. What I am afraid is that this fixes the symptoms instead of the
> underlaying problem. The problem I think is that with this large 1MB requests
> you risk of using the SWIOTLB bounce buffer which can result in poor
> performance.
> 
> So eventually somebody will have to figure out why the performance is poor
> and have a hard time figuring what is wrong - as the symptoms have been
> removed.
> 
> Hence looking at potentially using an scatter gather mechanism and chop up
> the requests in smaller sizes might be an better option. But I don't know?
> Perhaps you are more familiar with the gadget and could tell me why it needs
> an 1MB size request?
> 
> 
The 1M size is requested when doing flash fastboot in 
system/core/fastbootd/commands/flash.c  defined by Google.
I listed a partial code from flash.c  here.
#define BUFFER_SIZE 1024 * 1024
int current_size = MIN(size - written, BUFFER_SIZE);
(gpt_mmap(&input, written + skip, current_size, data_fd))
mapping->size = ALIGN(size + location_diff, PAGE_SIZE);

> >
> > Xiaoming.