Re: [PATCH v2 07/20] drm/amdgpu: allocate multiple clear entities

Christian König
2025-11-17T08:42:01Z

On 11/13/25 17:05, Pierre-Eric Pelloux-Prayer wrote:
> No functional change for now, as we always use entity 0.
>
> Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c | 11 +--
> drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c | 6 +-
> drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 2 +-
> drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 76 +++++++++++++--------
> drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h | 10 +--
> 5 files changed, 66 insertions(+), 39 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> index 2a444d02cf4b..e73dcfed5338 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> @@ -655,7 +655,7 @@ void amdgpu_gmc_flush_gpu_tlb(struct amdgpu_device *adev, uint32_t vmid,
> struct amdgpu_vmhub *hub = &adev->vmhub[vmhub];
> struct dma_fence *fence;
> struct amdgpu_job *job;
> - int r;
> + int r, i;
>
> if (!hub->sdma_invalidation_workaround || vmid ||
> !adev->mman.buffer_funcs_enabled || !adev->ib_pool_ready ||
> @@ -686,8 +686,9 @@ void amdgpu_gmc_flush_gpu_tlb(struct amdgpu_device *adev, uint32_t vmid,
> * translation. Avoid this by doing the invalidation from the SDMA
> * itself at least for GART.
> */
> - mutex_lock(&adev->mman.clear_entity.gart_window_lock);
> mutex_lock(&adev->mman.move_entity.gart_window_lock);
> + for (i = 0; i < adev->mman.num_clear_entities; i++)
> + mutex_lock(&adev->mman.clear_entities[i].gart_window_lock);

Ok, that here makes not much sense but I already pointed that out on the other patch, so let's discuss there.

> r = amdgpu_job_alloc_with_ib(ring->adev, &adev->mman.default_entity.base,
> AMDGPU_FENCE_OWNER_UNDEFINED,
> 16 * 4, AMDGPU_IB_POOL_IMMEDIATE,
> @@ -701,7 +702,8 @@ void amdgpu_gmc_flush_gpu_tlb(struct amdgpu_device *adev, uint32_t vmid,
> amdgpu_ring_pad_ib(ring, &job->ibs[0]);
> fence = amdgpu_job_submit(job);
> mutex_unlock(&adev->mman.move_entity.gart_window_lock);
> - mutex_unlock(&adev->mman.clear_entity.gart_window_lock);
> + for (i = 0; i < adev->mman.num_clear_entities; i++)
> + mutex_unlock(&adev->mman.clear_entities[i].gart_window_lock);
>
> dma_fence_wait(fence, false);
> dma_fence_put(fence);
> @@ -710,7 +712,8 @@ void amdgpu_gmc_flush_gpu_tlb(struct amdgpu_device *adev, uint32_t vmid,
>
> error_alloc:
> mutex_unlock(&adev->mman.move_entity.gart_window_lock);
> - mutex_unlock(&adev->mman.clear_entity.gart_window_lock);
> + for (i = 0; i < adev->mman.num_clear_entities; i++)
> + mutex_unlock(&adev->mman.clear_entities[i].gart_window_lock);
> dev_err(adev->dev, "Error flushing GPU TLB using the SDMA (%d)!\n", r);
> }
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
> index 0760e70402ec..3771e89035f5 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
> @@ -269,10 +269,12 @@ static const struct ttm_resource_manager_func amdgpu_gtt_mgr_func = {
> *
> * @adev: amdgpu_device pointer
> * @gtt_size: maximum size of GTT
> + * @reserved_windows: num of already used windows
> *
> * Allocate and initialize the GTT manager.
> */
> -int amdgpu_gtt_mgr_init(struct amdgpu_device *adev, uint64_t gtt_size)
> +int amdgpu_gtt_mgr_init(struct amdgpu_device *adev, uint64_t gtt_size,
> + u32 reserved_windows)
> {
> struct amdgpu_gtt_mgr *mgr = &adev->mman.gtt_mgr;
> struct ttm_resource_manager *man = &mgr->manager;
> @@ -283,7 +285,7 @@ int amdgpu_gtt_mgr_init(struct amdgpu_device *adev, uint64_t gtt_size)
>
> ttm_resource_manager_init(man, &adev->mman.bdev, gtt_size);
>
> - start = AMDGPU_GTT_MAX_TRANSFER_SIZE * AMDGPU_GTT_NUM_TRANSFER_WINDOWS;
> + start = AMDGPU_GTT_MAX_TRANSFER_SIZE * reserved_windows;

Probably best to separate this change out into it's own patch. E.g. something like "remove fixed AMDGPU_GTT_NUM_TRANSFER_WINDOWS"...

> size = (adev->gmc.gart_size >> PAGE_SHIFT) - start;
> drm_mm_init(&mgr->mm, start, size);
> spin_lock_init(&mgr->lock);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> index c06c132a753c..e7b2cae031b3 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> @@ -1321,7 +1321,7 @@ void amdgpu_bo_release_notify(struct ttm_buffer_object *bo)
> if (r)
> goto out;
>
> - r = amdgpu_fill_buffer(&adev->mman.clear_entity, abo, 0, &bo->base._resv,
> + r = amdgpu_fill_buffer(&adev->mman.clear_entities[0], abo, 0, &bo->base._resv,
> &fence, AMDGPU_KERNEL_JOB_ID_CLEAR_ON_RELEASE);
> if (WARN_ON(r))
> goto out;
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 7193a341689d..2f305ad32080 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -1891,6 +1891,7 @@ static void amdgpu_ttm_mmio_remap_bo_fini(struct amdgpu_device *adev)
> int amdgpu_ttm_init(struct amdgpu_device *adev)
> {
> uint64_t gtt_size;
> + u32 gart_window;

Make that num_gart_windows or reserved_windows or something like that.

> int r;
>
> dma_set_max_seg_size(adev->dev, UINT_MAX);
> @@ -1923,7 +1924,7 @@ int amdgpu_ttm_init(struct amdgpu_device *adev)
> }
>
> /* Change the size here instead of the init above so only lpfn is affected */
> - amdgpu_ttm_set_buffer_funcs_status(adev, false);
> + gart_window = amdgpu_ttm_set_buffer_funcs_status(adev, false);
> #ifdef CONFIG_64BIT
> #ifdef CONFIG_X86
> if (adev->gmc.xgmi.connected_to_cpu)
> @@ -2019,7 +2020,7 @@ int amdgpu_ttm_init(struct amdgpu_device *adev)
> }
>
> /* Initialize GTT memory pool */
> - r = amdgpu_gtt_mgr_init(adev, gtt_size);
> + r = amdgpu_gtt_mgr_init(adev, gtt_size, gart_window);
> if (r) {
> dev_err(adev->dev, "Failed initializing GTT heap.\n");
> return r;
> @@ -2158,16 +2159,22 @@ void amdgpu_ttm_fini(struct amdgpu_device *adev)
> *
> * Enable/disable use of buffer functions during suspend/resume. This should
> * only be called at bootup or when userspace isn't running.
> + *
> + * Returns: the number of GART reserved window
> */
> -void amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)
> +u32 amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)
> {
> struct ttm_resource_manager *man = ttm_manager_type(&adev->mman.bdev, TTM_PL_VRAM);
> uint64_t size;
> - int r, i;
> + int r, i, j;
> + u32 num_clear_entities, windows, w;
> +
> + num_clear_entities = adev->sdma.num_instances;
> + windows = adev->gmc.is_app_apu ? 0 : (2 + num_clear_entities);

Hui? That doesn't make much sense.

>
> if (!adev->mman.initialized || amdgpu_in_reset(adev) ||
> adev->mman.buffer_funcs_enabled == enable || adev->gmc.is_app_apu)

This also doesn't make much sense to begin with. Why are the SDMA functions disabled when is_app_apu is true?

Regards,
Christian.

> - return;
> + return windows;
>
> if (enable) {
> struct amdgpu_ring *ring;
> @@ -2180,19 +2187,9 @@ void amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)
> 1, NULL);
> if (r) {
> dev_err(adev->dev,
> - "Failed setting up TTM BO move entity (%d)\n",
> + "Failed setting up TTM BO eviction entity (%d)\n",
> r);
> - return;
> - }
> -
> - r = drm_sched_entity_init(&adev->mman.clear_entity.base,
> - DRM_SCHED_PRIORITY_NORMAL, &sched,
> - 1, NULL);
> - if (r) {
> - dev_err(adev->dev,
> - "Failed setting up TTM BO clear entity (%d)\n",
> - r);
> - goto error_free_entity;
> + return 0;
> }
>
> r = drm_sched_entity_init(&adev->mman.move_entity.base,
> @@ -2202,26 +2199,51 @@ void amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)
> dev_err(adev->dev,
> "Failed setting up TTM BO move entity (%d)\n",
> r);
> - drm_sched_entity_destroy(&adev->mman.clear_entity.base);
> goto error_free_entity;
> }
>
> + adev->mman.num_clear_entities = num_clear_entities;
> + adev->mman.clear_entities = kcalloc(num_clear_entities,
> + sizeof(struct amdgpu_ttm_buffer_entity),
> + GFP_KERNEL);
> + if (!adev->mman.clear_entities)
> + goto error_free_entity;
> +
> + for (i = 0; i < num_clear_entities; i++) {
> + r = drm_sched_entity_init(&adev->mman.clear_entities[i].base,
> + DRM_SCHED_PRIORITY_NORMAL, &sched,
> + 1, NULL);
> + if (r) {
> + for (j = 0; j < i; j++)
> + drm_sched_entity_destroy(
> + &adev->mman.clear_entities[j].base);
> + kfree(adev->mman.clear_entities);
> + goto error_free_entity;
> + }
> + }
> +
> /* Statically assign GART windows to each entity. */
> + w = 0;
> mutex_init(&adev->mman.default_entity.gart_window_lock);
> - adev->mman.move_entity.gart_window_id0 = 0;
> - adev->mman.move_entity.gart_window_id1 = 1;
> + adev->mman.move_entity.gart_window_id0 = w++;
> + adev->mman.move_entity.gart_window_id1 = w++;
> mutex_init(&adev->mman.move_entity.gart_window_lock);
> - /* Clearing entity doesn't use id0 */
> - adev->mman.clear_entity.gart_window_id1 = 2;
> - mutex_init(&adev->mman.clear_entity.gart_window_lock);
> + for (i = 0; i < num_clear_entities; i++) {
> + /* Clearing entities don't use id0 */
> + adev->mman.clear_entities[i].gart_window_id1 = w++;
> + mutex_init(&adev->mman.clear_entities[i].gart_window_lock);
> + }
> + WARN_ON(w != windows);
> } else {
> drm_sched_entity_destroy(&adev->mman.default_entity.base);
> - drm_sched_entity_destroy(&adev->mman.clear_entity.base);
> drm_sched_entity_destroy(&adev->mman.move_entity.base);
> + for (i = 0; i < num_clear_entities; i++)
> + drm_sched_entity_destroy(&adev->mman.clear_entities[i].base);
> for (i = 0; i < TTM_NUM_MOVE_FENCES; i++) {
> dma_fence_put(man->eviction_fences[i]);
> man->eviction_fences[i] = NULL;
> }
> + kfree(adev->mman.clear_entities);
> }
>
> /* this just adjusts TTM size idea, which sets lpfn to the correct value */
> @@ -2232,10 +2254,11 @@ void amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)
> man->size = size;
> adev->mman.buffer_funcs_enabled = enable;
>
> - return;
> + return windows;
>
> error_free_entity:
> drm_sched_entity_destroy(&adev->mman.default_entity.base);
> + return 0;
> }
>
> static int amdgpu_ttm_prepare_job(struct amdgpu_device *adev,
> @@ -2388,8 +2411,7 @@ int amdgpu_ttm_clear_buffer(struct amdgpu_bo *bo,
>
> if (!fence)
> return -EINVAL;
> -
> - entity = &adev->mman.clear_entity;
> + entity = &adev->mman.clear_entities[0];
> *fence = dma_fence_get_stub();
>
> amdgpu_res_first(bo->tbo.resource, 0, amdgpu_bo_size(bo), &cursor);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> index f4f762be9fdd..797f851a4578 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> @@ -39,7 +39,6 @@
> #define __AMDGPU_PL_NUM (TTM_PL_PRIV + 6)
>
> #define AMDGPU_GTT_MAX_TRANSFER_SIZE 512
> -#define AMDGPU_GTT_NUM_TRANSFER_WINDOWS 3
>
> extern const struct attribute_group amdgpu_vram_mgr_attr_group;
> extern const struct attribute_group amdgpu_gtt_mgr_attr_group;
> @@ -73,8 +72,9 @@ struct amdgpu_mman {
> struct mutex gtt_window_lock;
>
> struct amdgpu_ttm_buffer_entity default_entity; /* has no gart windows */
> - struct amdgpu_ttm_buffer_entity clear_entity;
> struct amdgpu_ttm_buffer_entity move_entity;
> + struct amdgpu_ttm_buffer_entity *clear_entities;
> + u32 num_clear_entities;
>
> struct amdgpu_vram_mgr vram_mgr;
> struct amdgpu_gtt_mgr gtt_mgr;
> @@ -134,7 +134,7 @@ struct amdgpu_copy_mem {
> #define AMDGPU_COPY_FLAGS_GET(value, field) \
> (((__u32)(value) >> AMDGPU_COPY_FLAGS_##field##_SHIFT) & AMDGPU_COPY_FLAGS_##field##_MASK)
>
> -int amdgpu_gtt_mgr_init(struct amdgpu_device *adev, uint64_t gtt_size);
> +int amdgpu_gtt_mgr_init(struct amdgpu_device *adev, uint64_t gtt_size, u32 reserved_windows);
> void amdgpu_gtt_mgr_fini(struct amdgpu_device *adev);
> int amdgpu_preempt_mgr_init(struct amdgpu_device *adev);
> void amdgpu_preempt_mgr_fini(struct amdgpu_device *adev);
> @@ -168,8 +168,8 @@ bool amdgpu_res_cpu_visible(struct amdgpu_device *adev,
>
> int amdgpu_ttm_init(struct amdgpu_device *adev);
> void amdgpu_ttm_fini(struct amdgpu_device *adev);
> -void amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev,
> - bool enable);
> +u32 amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev,
> + bool enable);
> int amdgpu_copy_buffer(struct amdgpu_ring *ring,
> struct drm_sched_entity *entity,
> uint64_t src_offset,