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From: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
To: Matthew Auld <matthew.auld@intel.com>, intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 06/20] drm/i915: add I915_BO_ALLOC_TOPDOWN
Date: Mon, 31 Jan 2022 16:28:16 +0100	[thread overview]
Message-ID: <de1de76a-c2cd-adc2-cfe3-50d40920aa26@linux.intel.com> (raw)
In-Reply-To: <20220126152155.3070602-7-matthew.auld@intel.com>

On 1/26/22 16:21, Matthew Auld wrote:
> If the user doesn't require CPU access for the buffer, then
> ALLOC_TOPDOWN should be used, in order to prioritise allocating in the
> non-mappable portion of LMEM.
>
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>

I was wondering how this would work best with user-space not supplying 
any hints. Thinking that mappable LMEM buffers would be a minority, 
wouldn't it be better to have TOPDOWN behaviour set by default. It would 
then be migrated to mappable only if needed. And if the first usage is a 
cpu-map it would either be mapped in system or immediately migrated from 
pageless to mappable LMEM?


> ---
>   drivers/gpu/drm/i915/gem/i915_gem_object_types.h | 15 +++++++++++----
>   drivers/gpu/drm/i915/gem/i915_gem_pages.c        |  3 +++
>   drivers/gpu/drm/i915/gem/i915_gem_region.c       |  5 +++++
>   drivers/gpu/drm/i915/gem/i915_gem_ttm.c          | 13 ++++++++++---
>   drivers/gpu/drm/i915/gt/intel_gt.c               |  4 +++-
>   drivers/gpu/drm/i915/i915_vma.c                  |  3 +++
>   drivers/gpu/drm/i915/intel_region_ttm.c          | 11 ++++++++---
>   drivers/gpu/drm/i915/selftests/mock_region.c     |  7 +------
>   8 files changed, 44 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> index 71e778ecaeb8..29285aaf0477 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> @@ -319,15 +319,22 @@ struct drm_i915_gem_object {
>   #define I915_BO_ALLOC_PM_VOLATILE BIT(4)
>   /* Object needs to be restored early using memcpy during resume */
>   #define I915_BO_ALLOC_PM_EARLY    BIT(5)
> +/*
> + * Object is likely never accessed by the CPU. This will prioritise the BO to be
> + * allocated in the non-mappable portion of lmem. This is merely a hint, and if
> + * dealing with userspace objects the CPU fault handler is free to ignore this.
> + */
> +#define I915_BO_ALLOC_TOPDOWN	  BIT(6)
>   #define I915_BO_ALLOC_FLAGS (I915_BO_ALLOC_CONTIGUOUS | \
>   			     I915_BO_ALLOC_VOLATILE | \
>   			     I915_BO_ALLOC_CPU_CLEAR | \
>   			     I915_BO_ALLOC_USER | \
>   			     I915_BO_ALLOC_PM_VOLATILE | \
> -			     I915_BO_ALLOC_PM_EARLY)
> -#define I915_BO_READONLY          BIT(6)
> -#define I915_TILING_QUIRK_BIT     7 /* unknown swizzling; do not release! */
> -#define I915_BO_PROTECTED         BIT(8)
> +			     I915_BO_ALLOC_PM_EARLY | \
> +			     I915_BO_ALLOC_TOPDOWN)
> +#define I915_BO_READONLY          BIT(7)
> +#define I915_TILING_QUIRK_BIT     8 /* unknown swizzling; do not release! */
> +#define I915_BO_PROTECTED         BIT(9)
>   	/**
>   	 * @mem_flags - Mutable placement-related flags
>   	 *
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pages.c b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
> index 7d2211fbe548..a95b4d72619f 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_pages.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
> @@ -346,6 +346,9 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
>   	    !i915_gem_object_has_iomem(obj))
>   		return ERR_PTR(-ENXIO);
>   
> +	if (WARN_ON_ONCE(obj->flags & I915_BO_ALLOC_TOPDOWN))
> +		return ERR_PTR(-EINVAL);
> +
>   	assert_object_held(obj);
>   
>   	pinned = !(type & I915_MAP_OVERRIDE);
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_region.c b/drivers/gpu/drm/i915/gem/i915_gem_region.c
> index a4350227e9ae..f91e5a9c759d 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_region.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_region.c
> @@ -45,6 +45,11 @@ i915_gem_object_create_region(struct intel_memory_region *mem,
>   
>   	GEM_BUG_ON(flags & ~I915_BO_ALLOC_FLAGS);
>   
> +	if (WARN_ON_ONCE(flags & I915_BO_ALLOC_TOPDOWN &&
> +			 (flags & I915_BO_ALLOC_CPU_CLEAR ||
> +			  flags & I915_BO_ALLOC_PM_EARLY)))
> +		return ERR_PTR(-EINVAL);
> +
>   	if (!mem)
>   		return ERR_PTR(-ENODEV);
>   
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> index d9a04c7d41b1..e60b677ecd54 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> @@ -127,10 +127,14 @@ i915_ttm_place_from_region(const struct intel_memory_region *mr,
>   	place->mem_type = intel_region_to_ttm_type(mr);
>   
>   	if (flags & I915_BO_ALLOC_CONTIGUOUS)
> -		place->flags = TTM_PL_FLAG_CONTIGUOUS;
> +		place->flags |= TTM_PL_FLAG_CONTIGUOUS;
>   	if (mr->io_size && mr->io_size < mr->total) {
> -		place->fpfn = 0;
> -		place->lpfn = mr->io_size >> PAGE_SHIFT;
> +		if (flags & I915_BO_ALLOC_TOPDOWN) {
> +			place->flags |= TTM_PL_FLAG_TOPDOWN;
> +		} else {
> +			place->fpfn = 0;
> +			place->lpfn = mr->io_size >> PAGE_SHIFT;
> +		}
>   	}
>   }
>   
> @@ -890,6 +894,9 @@ static vm_fault_t vm_fault_ttm(struct vm_fault *vmf)
>   	if (!obj)
>   		return VM_FAULT_SIGBUS;
>   
> +	if (obj->flags & I915_BO_ALLOC_TOPDOWN)
> +		return -EINVAL;
> +
>   	/* Sanity check that we allow writing into this object */
>   	if (unlikely(i915_gem_object_is_readonly(obj) &&
>   		     area->vm_flags & VM_WRITE))
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt.c b/drivers/gpu/drm/i915/gt/intel_gt.c
> index 622cdfed8a8b..8b83a771a2f7 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt.c
> +++ b/drivers/gpu/drm/i915/gt/intel_gt.c
> @@ -454,7 +454,9 @@ static int intel_gt_init_scratch(struct intel_gt *gt, unsigned int size)
>   	struct i915_vma *vma;
>   	int ret;
>   
> -	obj = i915_gem_object_create_lmem(i915, size, I915_BO_ALLOC_VOLATILE);
> +	obj = i915_gem_object_create_lmem(i915, size,
> +					  I915_BO_ALLOC_VOLATILE |
> +					  I915_BO_ALLOC_TOPDOWN);
>   	if (IS_ERR(obj))
>   		obj = i915_gem_object_create_stolen(i915, size);
>   	if (IS_ERR(obj))
> diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
> index b1816a835abf..b2fdaa74e4b6 100644
> --- a/drivers/gpu/drm/i915/i915_vma.c
> +++ b/drivers/gpu/drm/i915/i915_vma.c
> @@ -528,6 +528,9 @@ void __iomem *i915_vma_pin_iomap(struct i915_vma *vma)
>   	void __iomem *ptr;
>   	int err;
>   
> +	if (WARN_ON_ONCE(vma->obj->flags & I915_BO_ALLOC_TOPDOWN))
> +		return IO_ERR_PTR(-EINVAL);
> +
>   	if (!i915_gem_object_is_lmem(vma->obj)) {
>   		if (GEM_WARN_ON(!i915_vma_is_map_and_fenceable(vma))) {
>   			err = -ENODEV;
> diff --git a/drivers/gpu/drm/i915/intel_region_ttm.c b/drivers/gpu/drm/i915/intel_region_ttm.c
> index 4689192d5e8d..282802aed174 100644
> --- a/drivers/gpu/drm/i915/intel_region_ttm.c
> +++ b/drivers/gpu/drm/i915/intel_region_ttm.c
> @@ -199,13 +199,18 @@ intel_region_ttm_resource_alloc(struct intel_memory_region *mem,
>   	struct ttm_resource *res;
>   	int ret;
>   
> +	if (flags & I915_BO_ALLOC_CONTIGUOUS)
> +		place.flags |= TTM_PL_FLAG_CONTIGUOUS;
>   	if (mem->io_size && mem->io_size < mem->total) {
> -		place.fpfn = 0;
> -		place.lpfn = mem->io_size >> PAGE_SHIFT;
> +		if (flags & I915_BO_ALLOC_TOPDOWN) {
> +			place.flags |= TTM_PL_FLAG_TOPDOWN;
> +		} else {
> +			place.fpfn = 0;
> +			place.lpfn = mem->io_size >> PAGE_SHIFT;
> +		}
>   	}
>   
>   	mock_bo.base.size = size;
> -	place.flags = flags;
>   
>   	ret = man->func->alloc(man, &mock_bo, &place, &res);
>   	if (ret == -ENOSPC)
> diff --git a/drivers/gpu/drm/i915/selftests/mock_region.c b/drivers/gpu/drm/i915/selftests/mock_region.c
> index 467eeae6d5f0..f64325491f35 100644
> --- a/drivers/gpu/drm/i915/selftests/mock_region.c
> +++ b/drivers/gpu/drm/i915/selftests/mock_region.c
> @@ -22,17 +22,12 @@ static void mock_region_put_pages(struct drm_i915_gem_object *obj,
>   
>   static int mock_region_get_pages(struct drm_i915_gem_object *obj)
>   {
> -	unsigned int flags;
>   	struct sg_table *pages;
>   	int err;
>   
> -	flags = 0;
> -	if (obj->flags & I915_BO_ALLOC_CONTIGUOUS)
> -		flags |= TTM_PL_FLAG_CONTIGUOUS;
> -
>   	obj->mm.res = intel_region_ttm_resource_alloc(obj->mm.region,
>   						      obj->base.size,
> -						      flags);
> +						      obj->flags);
>   	if (IS_ERR(obj->mm.res))
>   		return PTR_ERR(obj->mm.res);
>   

  reply	other threads:[~2022-01-31 15:28 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-26 15:21 [PATCH 00/20] Initial support for small BAR recovery Matthew Auld
2022-01-26 15:21 ` [PATCH 01/20] drm: improve drm_buddy_alloc function Matthew Auld
2022-01-26 18:03   ` [Intel-gfx] " Jani Nikula
2022-01-26 15:21 ` [PATCH 02/20] drm: implement top-down allocation method Matthew Auld
2022-01-26 18:42   ` [Intel-gfx] " Robert Beckett
2022-01-26 15:21 ` [PATCH 03/20] drm: implement a method to free unused pages Matthew Auld
2022-01-26 15:21 ` [PATCH 04/20] drm/i915: add io_size plumbing Matthew Auld
2022-01-31 15:14   ` Thomas Hellström
2022-01-26 15:21 ` [PATCH 05/20] drm/i915/ttm: require mappable by default Matthew Auld
2022-01-26 15:21 ` [PATCH 06/20] drm/i915: add I915_BO_ALLOC_TOPDOWN Matthew Auld
2022-01-31 15:28   ` Thomas Hellström [this message]
2022-01-31 15:49     ` Matthew Auld
2022-01-26 15:21 ` [PATCH 07/20] drm/i915/buddy: track available visible size Matthew Auld
2022-01-31 16:12   ` Thomas Hellström
2022-01-26 15:21 ` [PATCH 08/20] drm/i915/buddy: adjust res->start Matthew Auld
2022-02-01 10:38   ` Thomas Hellström
2022-01-26 15:21 ` [PATCH 09/20] drm/i915/buddy: tweak 2big check Matthew Auld
2022-02-01 10:39   ` Thomas Hellström
2022-01-26 15:21 ` [PATCH 10/20] drm/i915/selftests: mock test io_size Matthew Auld
2022-02-02 10:24   ` Thomas Hellström
2022-01-26 15:21 ` [PATCH 11/20] drm/i915/ttm: tweak priority hint selection Matthew Auld
2022-02-02 13:34   ` Thomas Hellström
2022-01-26 15:21 ` [PATCH 12/20] drm/i915/ttm: make eviction mappable aware Matthew Auld
2022-02-02 13:41   ` Thomas Hellström
2022-01-26 15:21 ` [PATCH 13/20] drm/i915/ttm: mappable migration on fault Matthew Auld
2022-02-03  7:59   ` Thomas Hellström
2022-01-26 15:21 ` [PATCH 14/20] drm/i915/selftests: exercise mmap migration Matthew Auld
2022-02-03  9:01   ` Thomas Hellström
2022-02-03  9:12     ` Matthew Auld
2022-01-26 15:21 ` [PATCH 15/20] drm/i915/selftests: handle allocation failures Matthew Auld
2022-02-03  9:05   ` Thomas Hellström
2022-02-03  9:11     ` Matthew Auld
2022-01-26 15:21 ` [PATCH 16/20] drm/i915/create: apply ALLOC_TOPDOWN by default Matthew Auld
2022-02-03  9:17   ` Thomas Hellström
2022-02-03  9:32     ` Matthew Auld
2022-01-26 15:21 ` [PATCH 17/20] drm/i915/uapi: add NEEDS_CPU_ACCESS hint Matthew Auld
2022-02-03  9:28   ` Thomas Hellström
2022-02-03 11:38     ` Matthew Auld
2022-02-03 13:29       ` Thomas Hellström
2022-01-26 15:21 ` [PATCH 18/20] drm/i915/uapi: forbid ALLOC_TOPDOWN for error capture Matthew Auld
2022-01-26 19:42   ` [Intel-gfx] " kernel test robot
2022-01-26 20:03   ` kernel test robot
2022-02-03  9:43   ` Thomas Hellström
2022-02-03  9:44     ` Matthew Auld
2022-01-26 15:21 ` [PATCH 19/20] drm/i915/lmem: don't treat small BAR as an error Matthew Auld
2022-02-03  9:48   ` Thomas Hellström
2022-02-03 11:18     ` Matthew Auld
2022-02-03 13:56       ` Thomas Hellström
2022-02-03 14:09         ` Matthew Auld
2022-01-26 15:21 ` [PATCH 20/20] HAX: DG1 small BAR Matthew Auld

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