Am 2021-04-26 um 4:54 a.m. schrieb Christian König:
> Merge the two loops, loosen the restriction for big allocations.
> This reduces the CPU overhead in the good case, but increases
> it a bit under memory pressure.
>
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 58 +++++++++-----------
> 1 file changed, 27 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> index 529c5c32a205..e2cbe19404c0 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> @@ -358,13 +358,13 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
> const struct ttm_place *place,
> struct ttm_resource *mem)
> {
> + unsigned long lpfn, num_nodes, pages_per_node, pages_left, pages;
> struct amdgpu_vram_mgr *mgr = to_vram_mgr(man);
> struct amdgpu_device *adev = to_amdgpu_device(mgr);
> + uint64_t vis_usage = 0, mem_bytes, max_bytes;
> struct drm_mm *mm = &mgr->mm;
> - struct drm_mm_node *nodes;
> enum drm_mm_insert_mode mode;
> - unsigned long lpfn, num_nodes, pages_per_node, pages_left;
> - uint64_t vis_usage = 0, mem_bytes, max_bytes;
> + struct drm_mm_node *nodes;
> unsigned i;
> int r;
>
> @@ -391,9 +391,10 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
> pages_per_node = HPAGE_PMD_NR;
> #else
> /* default to 2MB */
> - pages_per_node = (2UL << (20UL - PAGE_SHIFT));
> + pages_per_node = 2UL << (20UL - PAGE_SHIFT);
> #endif
> - pages_per_node = max((uint32_t)pages_per_node, mem->page_alignment);
> + pages_per_node = max_t(uint32_t, pages_per_node,
> + mem->page_alignment);
> num_nodes = DIV_ROUND_UP(mem->num_pages, pages_per_node);
> }
>
> @@ -411,42 +412,37 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
> mem->start = 0;
> pages_left = mem->num_pages;
>
> - spin_lock(&mgr->lock);
> - for (i = 0; pages_left >= pages_per_node; ++i) {
> - unsigned long pages = rounddown_pow_of_two(pages_left);
> -
> - /* Limit maximum size to 2GB due to SG table limitations */
> - pages = min(pages, (2UL << (30 - PAGE_SHIFT)));
> + /* Limit maximum size to 2GB due to SG table limitations */
> + pages = min(pages_left, 2UL << (30 - PAGE_SHIFT));
>
> - r = drm_mm_insert_node_in_range(mm, &nodes[i], pages,
> - pages_per_node, 0,
> - place->fpfn, lpfn,
> - mode);
> - if (unlikely(r))
> - break;
> -
> - vis_usage += amdgpu_vram_mgr_vis_size(adev, &nodes[i]);
> - amdgpu_vram_mgr_virt_start(mem, &nodes[i]);
> - pages_left -= pages;
> - }
> -
> - for (; pages_left; ++i) {
> - unsigned long pages = min(pages_left, pages_per_node);
> + i = 0;
> + spin_lock(&mgr->lock);
> + while (pages_left) {
> uint32_t alignment = mem->page_alignment;
>
> - if (pages == pages_per_node)
> + if (pages >= pages_per_node)
> alignment = pages_per_node;
>
> - r = drm_mm_insert_node_in_range(mm, &nodes[i],
> - pages, alignment, 0,
> - place->fpfn, lpfn,
> - mode);
> - if (unlikely(r))
> + r = drm_mm_insert_node_in_range(mm, &nodes[i], pages, alignment,
> + 0, place->fpfn, lpfn, mode);
> + if (unlikely(r)) {
> + if (pages > pages_per_node) {
This means we can never allocate chunks smaller than 2MB, except for the
tail. And the tail still needs to be allocated in one piece if it's < 2MB.
On the other hand, we should not allow allocations smaller than
mem->page_alignment, except for the tail. So should this condition be
"if (pages > mem->page_alignment)" to allow maximum flexibility for
allocations without physical alignment constraints when memory is very
fragmented?
Regards,
Felix
> + if (is_power_of_2(pages))
> + pages = pages / 2;
> + else
> + pages = rounddown_pow_of_two(pages);
> + continue;
> + }
> goto error;
> + }
>
> vis_usage += amdgpu_vram_mgr_vis_size(adev, &nodes[i]);
> amdgpu_vram_mgr_virt_start(mem, &nodes[i]);
> pages_left -= pages;
> + ++i;
> +
> + if (pages > pages_left)
> + pages = pages_left;
> }
> spin_unlock(&mgr->lock);
>
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