[PATCH] dma-debug: hns_enet_drv could use more DMA entries

[PATCH] dma-debug: hns_enet_drv could use more DMA entries

[Qian Cai]

The amount of DMA mappings from Hisilicon HNS ethernet devices is huge,
so it could trigger "DMA-API: debugging out of memory - disabling".

hnae_get_handle [1]
  hnae_init_queue
    hnae_init_ring
      hnae_alloc_buffers [2]
        debug_dma_map_page
          dma_entry_alloc

[1] for (i = 0; i < handle->q_num; i++)
[2] for (i = 0; i < ring->desc_num; i++)

On this Huawei TaiShan 2280 aarch64 server, it has reached the limit
already,

4 (ports) x 16 (handles) x 1024 (rings) = 65536

Signed-off-by: Qian Cai <cai@gmx.us>
---
 kernel/dma/debug.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
index 231ca4628062..ae91689cc9ad 100644
--- a/kernel/dma/debug.c
+++ b/kernel/dma/debug.c
@@ -43,8 +43,13 @@
 
 /* allow architectures to override this if absolutely required */
 #ifndef PREALLOC_DMA_DEBUG_ENTRIES
+/* amount of DMA mappings on this driver is huge. */
+#ifdef	HNS_ENET
+#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 17)
+#else
 #define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
 #endif
+#endif
 
 enum {
 	dma_debug_single,
-- 
2.17.2 (Apple Git-113)

Re: [PATCH] dma-debug: hns_enet_drv could use more DMA entries

[Christoph Hellwig]

On Thu, Nov 29, 2018 at 10:54:56PM -0500, Qian Cai wrote:
>  /* allow architectures to override this if absolutely required */
>  #ifndef PREALLOC_DMA_DEBUG_ENTRIES
> +/* amount of DMA mappings on this driver is huge. */
> +#ifdef	HNS_ENET
> +#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 17)
> +#else
>  #define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
>  #endif
> +#endif

How would this be defined in a header that leaks into this file?

I think we need to turn PREALLOC_DMA_DEBUG_ENTRIES into a user
selectable config options, as I really don't want to collect hacks like
this.

Re: [PATCH] dma-debug: hns_enet_drv could use more DMA entries

[John Garry]

+

Pasting original message at bottom.


On 30/11/2018 08:42, Christoph Hellwig wrote:
> On Thu, Nov 29, 2018 at 10:54:56PM -0500, Qian Cai wrote:
>>  /* allow architectures to override this if absolutely required */
>>  #ifndef PREALLOC_DMA_DEBUG_ENTRIES
>> +/* amount of DMA mappings on this driver is huge. */
>> +#ifdef	HNS_ENET
>> +#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 17)
>> +#else
>>  #define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
>>  #endif
>> +#endif
>
> How would this be defined in a header that leaks into this file?
>
> I think we need to turn PREALLOC_DMA_DEBUG_ENTRIES into a user
> selectable config options, as I really don't want to collect hacks like
> this.
> _______________________________________________
> iommu mailing list
> iommu@lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu
>
>







The amount of DMA mappings from Hisilicon HNS ethernet devices is huge,
so it could trigger "DMA-API: debugging out of memory - disabling".

hnae_get_handle [1]
   hnae_init_queue
     hnae_init_ring
       hnae_alloc_buffers [2]
         debug_dma_map_page
           dma_entry_alloc

[1] for (i = 0; i < handle->q_num; i++)
[2] for (i = 0; i < ring->desc_num; i++)

On this Huawei TaiShan 2280 aarch64 server, it has reached the limit
already,

4 (ports) x 16 (handles) x 1024 (rings) = 65536

Signed-off-by: Qian Cai <cai@gmx.us>
---
  kernel/dma/debug.c | 5 +++++
  1 file changed, 5 insertions(+)

diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
index 231ca4628062..ae91689cc9ad 100644
--- a/kernel/dma/debug.c
+++ b/kernel/dma/debug.c
@@ -43,8 +43,13 @@

  /* allow architectures to override this if absolutely required */
  #ifndef PREALLOC_DMA_DEBUG_ENTRIES
+/* amount of DMA mappings on this driver is huge. */
+#ifdef	HNS_ENET
+#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 17)
+#else
  #define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
  #endif
+#endif

  enum {
  	dma_debug_single,

Re: [PATCH] dma-debug: hns_enet_drv could use more DMA entries

[Robin Murphy]

On 30/11/2018 08:42, Christoph Hellwig wrote:
> On Thu, Nov 29, 2018 at 10:54:56PM -0500, Qian Cai wrote:
>>   /* allow architectures to override this if absolutely required */
>>   #ifndef PREALLOC_DMA_DEBUG_ENTRIES
>> +/* amount of DMA mappings on this driver is huge. */
>> +#ifdef	HNS_ENET
>> +#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 17)
>> +#else
>>   #define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
>>   #endif
>> +#endif
> 
> How would this be defined in a header that leaks into this file?

Apparently it wouldn't, because nothing defines that macro anywhere 
anyway. CONFIG_HNS_ENET, on the other hand, would be available by virtue 
of autoconf.h which is just about everywhere.

> I think we need to turn PREALLOC_DMA_DEBUG_ENTRIES into a user
> selectable config options, as I really don't want to collect hacks like
> this.

Agreed - we already have per-arch overrides scattered about, so growing 
special cases in yet another place just makes even more of a mess. 
Rounding all of it up into Kconfig would definitely make sense.

Robin.