Re: [PATCH 3/3] drm/ttm: switch to per device LRU lock

[Christian König <ckoenig.leichtzumerken@xxxxxxxxx>]

Am 19.03.21 um 05:32 schrieb Huang Rui:
> On Thu, Mar 18, 2021 at 08:47:19PM +0800, Christian König wrote:
> > Instead of having a global lock.
> >
> > Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> > ---
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c |  8 ++---
> >   drivers/gpu/drm/qxl/qxl_release.c      |  5 +--
> >   drivers/gpu/drm/ttm/ttm_bo.c           | 49 ++++++++++++--------------
> >   drivers/gpu/drm/ttm/ttm_device.c       | 12 +++----
> >   drivers/gpu/drm/ttm/ttm_execbuf_util.c |  8 ++---
> >   drivers/gpu/drm/ttm/ttm_resource.c     |  9 +++--
> >   include/drm/ttm/ttm_bo_driver.h        |  4 +--
> >   include/drm/ttm/ttm_device.h           |  4 +--
> >   8 files changed, 43 insertions(+), 56 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > index 9d19078246c8..ae18c0e32347 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > @@ -638,15 +638,15 @@ void amdgpu_vm_move_to_lru_tail(struct amdgpu_device *adev,
> >   	struct amdgpu_vm_bo_base *bo_base;
> >   
> >   	if (vm->bulk_moveable) {
> > -		spin_lock(&ttm_glob.lru_lock);
> > +		spin_lock(&adev->mman.bdev.lru_lock);
> Could you please explain why do you want to instead of the global lock?

Potentially less contention.

But you are right mentioning this in the commit message is a good idea.

Regards,
Christian.

> Thanks,
> Ray
>
> >   		ttm_bo_bulk_move_lru_tail(&vm->lru_bulk_move);
> > -		spin_unlock(&ttm_glob.lru_lock);
> > +		spin_unlock(&adev->mman.bdev.lru_lock);
> >   		return;
> >   	}
> >   
> >   	memset(&vm->lru_bulk_move, 0, sizeof(vm->lru_bulk_move));
> >   
> > -	spin_lock(&ttm_glob.lru_lock);
> > +	spin_lock(&adev->mman.bdev.lru_lock);
> >   	list_for_each_entry(bo_base, &vm->idle, vm_status) {
> >   		struct amdgpu_bo *bo = bo_base->bo;
> >   
> > @@ -660,7 +660,7 @@ void amdgpu_vm_move_to_lru_tail(struct amdgpu_device *adev,
> >   						&bo->shadow->tbo.mem,
> >   						&vm->lru_bulk_move);
> >   	}
> > -	spin_unlock(&ttm_glob.lru_lock);
> > +	spin_unlock(&adev->mman.bdev.lru_lock);
> >   
> >   	vm->bulk_moveable = true;
> >   }
> > diff --git a/drivers/gpu/drm/qxl/qxl_release.c b/drivers/gpu/drm/qxl/qxl_release.c
> > index f5845c96d414..b19f2f00b215 100644
> > --- a/drivers/gpu/drm/qxl/qxl_release.c
> > +++ b/drivers/gpu/drm/qxl/qxl_release.c
> > @@ -426,16 +426,13 @@ void qxl_release_fence_buffer_objects(struct qxl_release *release)
> >   		       release->id | 0xf0000000, release->base.seqno);
> >   	trace_dma_fence_emit(&release->base);
> >   
> > -	spin_lock(&ttm_glob.lru_lock);
> > -
> >   	list_for_each_entry(entry, &release->bos, head) {
> >   		bo = entry->bo;
> >   
> >   		dma_resv_add_shared_fence(bo->base.resv, &release->base);
> > -		ttm_bo_move_to_lru_tail(bo, &bo->mem, NULL);
> > +		ttm_bo_move_to_lru_tail_unlocked(bo);
> >   		dma_resv_unlock(bo->base.resv);
> >   	}
> > -	spin_unlock(&ttm_glob.lru_lock);
> >   	ww_acquire_fini(&release->ticket);
> >   }
> >   
> > diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> > index 3673157527ff..2d2ac532987e 100644
> > --- a/drivers/gpu/drm/ttm/ttm_bo.c
> > +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> > @@ -243,9 +243,9 @@ static int ttm_bo_individualize_resv(struct ttm_buffer_object *bo)
> >   		 * reference it any more. The only tricky case is the trylock on
> >   		 * the resv object while holding the lru_lock.
> >   		 */
> > -		spin_lock(&ttm_glob.lru_lock);
> > +		spin_lock(&bo->bdev->lru_lock);
> >   		bo->base.resv = &bo->base._resv;
> > -		spin_unlock(&ttm_glob.lru_lock);
> > +		spin_unlock(&bo->bdev->lru_lock);
> >   	}
> >   
> >   	return r;
> > @@ -304,7 +304,7 @@ static int ttm_bo_cleanup_refs(struct ttm_buffer_object *bo,
> >   
> >   		if (unlock_resv)
> >   			dma_resv_unlock(bo->base.resv);
> > -		spin_unlock(&ttm_glob.lru_lock);
> > +		spin_unlock(&bo->bdev->lru_lock);
> >   
> >   		lret = dma_resv_wait_timeout_rcu(resv, true, interruptible,
> >   						 30 * HZ);
> > @@ -314,7 +314,7 @@ static int ttm_bo_cleanup_refs(struct ttm_buffer_object *bo,
> >   		else if (lret == 0)
> >   			return -EBUSY;
> >   
> > -		spin_lock(&ttm_glob.lru_lock);
> > +		spin_lock(&bo->bdev->lru_lock);
> >   		if (unlock_resv && !dma_resv_trylock(bo->base.resv)) {
> >   			/*
> >   			 * We raced, and lost, someone else holds the reservation now,
> > @@ -324,7 +324,7 @@ static int ttm_bo_cleanup_refs(struct ttm_buffer_object *bo,
> >   			 * delayed destruction would succeed, so just return success
> >   			 * here.
> >   			 */
> > -			spin_unlock(&ttm_glob.lru_lock);
> > +			spin_unlock(&bo->bdev->lru_lock);
> >   			return 0;
> >   		}
> >   		ret = 0;
> > @@ -333,13 +333,13 @@ static int ttm_bo_cleanup_refs(struct ttm_buffer_object *bo,
> >   	if (ret || unlikely(list_empty(&bo->ddestroy))) {
> >   		if (unlock_resv)
> >   			dma_resv_unlock(bo->base.resv);
> > -		spin_unlock(&ttm_glob.lru_lock);
> > +		spin_unlock(&bo->bdev->lru_lock);
> >   		return ret;
> >   	}
> >   
> >   	ttm_bo_del_from_lru(bo);
> >   	list_del_init(&bo->ddestroy);
> > -	spin_unlock(&ttm_glob.lru_lock);
> > +	spin_unlock(&bo->bdev->lru_lock);
> >   	ttm_bo_cleanup_memtype_use(bo);
> >   
> >   	if (unlock_resv)
> > @@ -356,13 +356,12 @@ static int ttm_bo_cleanup_refs(struct ttm_buffer_object *bo,
> >    */
> >   bool ttm_bo_delayed_delete(struct ttm_device *bdev, bool remove_all)
> >   {
> > -	struct ttm_global *glob = &ttm_glob;
> >   	struct list_head removed;
> >   	bool empty;
> >   
> >   	INIT_LIST_HEAD(&removed);
> >   
> > -	spin_lock(&glob->lru_lock);
> > +	spin_lock(&bdev->lru_lock);
> >   	while (!list_empty(&bdev->ddestroy)) {
> >   		struct ttm_buffer_object *bo;
> >   
> > @@ -373,24 +372,24 @@ bool ttm_bo_delayed_delete(struct ttm_device *bdev, bool remove_all)
> >   			continue;
> >   
> >   		if (remove_all || bo->base.resv != &bo->base._resv) {
> > -			spin_unlock(&glob->lru_lock);
> > +			spin_unlock(&bdev->lru_lock);
> >   			dma_resv_lock(bo->base.resv, NULL);
> >   
> > -			spin_lock(&glob->lru_lock);
> > +			spin_lock(&bdev->lru_lock);
> >   			ttm_bo_cleanup_refs(bo, false, !remove_all, true);
> >   
> >   		} else if (dma_resv_trylock(bo->base.resv)) {
> >   			ttm_bo_cleanup_refs(bo, false, !remove_all, true);
> >   		} else {
> > -			spin_unlock(&glob->lru_lock);
> > +			spin_unlock(&bdev->lru_lock);
> >   		}
> >   
> >   		ttm_bo_put(bo);
> > -		spin_lock(&glob->lru_lock);
> > +		spin_lock(&bdev->lru_lock);
> >   	}
> >   	list_splice_tail(&removed, &bdev->ddestroy);
> >   	empty = list_empty(&bdev->ddestroy);
> > -	spin_unlock(&glob->lru_lock);
> > +	spin_unlock(&bdev->lru_lock);
> >   
> >   	return empty;
> >   }
> > @@ -425,7 +424,7 @@ static void ttm_bo_release(struct kref *kref)
> >   		ttm_bo_flush_all_fences(bo);
> >   		bo->deleted = true;
> >   
> > -		spin_lock(&ttm_glob.lru_lock);
> > +		spin_lock(&bo->bdev->lru_lock);
> >   
> >   		/*
> >   		 * Make pinned bos immediately available to
> > @@ -442,17 +441,17 @@ static void ttm_bo_release(struct kref *kref)
> >   
> >   		kref_init(&bo->kref);
> >   		list_add_tail(&bo->ddestroy, &bdev->ddestroy);
> > -		spin_unlock(&ttm_glob.lru_lock);
> > +		spin_unlock(&bo->bdev->lru_lock);
> >   
> >   		schedule_delayed_work(&bdev->wq,
> >   				      ((HZ / 100) < 1) ? 1 : HZ / 100);
> >   		return;
> >   	}
> >   
> > -	spin_lock(&ttm_glob.lru_lock);
> > +	spin_lock(&bo->bdev->lru_lock);
> >   	ttm_bo_del_from_lru(bo);
> >   	list_del(&bo->ddestroy);
> > -	spin_unlock(&ttm_glob.lru_lock);
> > +	spin_unlock(&bo->bdev->lru_lock);
> >   
> >   	ttm_bo_cleanup_memtype_use(bo);
> >   	dma_resv_unlock(bo->base.resv);
> > @@ -626,7 +625,7 @@ int ttm_mem_evict_first(struct ttm_device *bdev,
> >   	unsigned i;
> >   	int ret;
> >   
> > -	spin_lock(&ttm_glob.lru_lock);
> > +	spin_lock(&bo->bdev->lru_lock);
> >   	for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i) {
> >   		list_for_each_entry(bo, &man->lru[i], lru) {
> >   			bool busy;
> > @@ -663,7 +662,7 @@ int ttm_mem_evict_first(struct ttm_device *bdev,
> >   	if (!bo) {
> >   		if (busy_bo && !ttm_bo_get_unless_zero(busy_bo))
> >   			busy_bo = NULL;
> > -		spin_unlock(&ttm_glob.lru_lock);
> > +		spin_unlock(&bo->bdev->lru_lock);
> >   		ret = ttm_mem_evict_wait_busy(busy_bo, ctx, ticket);
> >   		if (busy_bo)
> >   			ttm_bo_put(busy_bo);
> > @@ -677,7 +676,7 @@ int ttm_mem_evict_first(struct ttm_device *bdev,
> >   		return ret;
> >   	}
> >   
> > -	spin_unlock(&ttm_glob.lru_lock);
> > +	spin_unlock(&bo->bdev->lru_lock);
> >   
> >   	ret = ttm_bo_evict(bo, ctx);
> >   	if (locked)
> > @@ -777,10 +776,9 @@ static int ttm_bo_mem_placement(struct ttm_buffer_object *bo,
> >   	mem->mem_type = place->mem_type;
> >   	mem->placement = place->flags;
> >   
> > -	spin_lock(&ttm_glob.lru_lock);
> > +	spin_lock(&bo->bdev->lru_lock);
> >   	ttm_bo_move_to_lru_tail(bo, mem, NULL);
> > -	spin_unlock(&ttm_glob.lru_lock);
> > -
> > +	spin_unlock(&bo->bdev->lru_lock);
> >   	return 0;
> >   }
> >   
> > @@ -1167,7 +1165,6 @@ EXPORT_SYMBOL(ttm_bo_wait);
> >   int ttm_bo_swapout(struct ttm_buffer_object *bo, struct ttm_operation_ctx *ctx,
> >   		   gfp_t gfp_flags)
> >   {
> > -	struct ttm_global *glob = &ttm_glob;
> >   	bool locked;
> >   	int ret;
> >   
> > @@ -1188,7 +1185,7 @@ int ttm_bo_swapout(struct ttm_buffer_object *bo, struct ttm_operation_ctx *ctx,
> >   
> >   	ttm_bo_del_from_lru(bo);
> >   	/* TODO: Cleanup the locking */
> > -	spin_unlock(&glob->lru_lock);
> > +	spin_unlock(&bo->bdev->lru_lock);
> >   
> >   	/*
> >   	 * Move to system cached
> > diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c
> > index 2096a0fd9c35..85f6975d9872 100644
> > --- a/drivers/gpu/drm/ttm/ttm_device.c
> > +++ b/drivers/gpu/drm/ttm/ttm_device.c
> > @@ -81,7 +81,6 @@ static int ttm_global_init(void)
> >   	ttm_pool_mgr_init(num_pages * 50 / 100);
> >   	ttm_tt_mgr_init();
> >   
> > -	spin_lock_init(&glob->lru_lock);
> >   	glob->dummy_read_page = alloc_page(__GFP_ZERO | GFP_DMA32);
> >   
> >   	if (unlikely(glob->dummy_read_page == NULL)) {
> > @@ -125,13 +124,12 @@ EXPORT_SYMBOL(ttm_global_swapout);
> >   long ttm_device_swapout(struct ttm_device *bdev, struct ttm_operation_ctx *ctx,
> >   			gfp_t gfp_flags)
> >   {
> > -	struct ttm_global *glob = &ttm_glob;
> >   	struct ttm_resource_manager *man;
> >   	struct ttm_buffer_object *bo;
> >   	unsigned i, j;
> >   	int ret;
> >   
> > -	spin_lock(&glob->lru_lock);
> > +	spin_lock(&bdev->lru_lock);
> >   	for (i = TTM_PL_SYSTEM; i < TTM_NUM_MEM_TYPES; ++i) {
> >   		man = ttm_manager_type(bdev, i);
> >   		if (!man || !man->use_tt)
> > @@ -156,7 +154,7 @@ long ttm_device_swapout(struct ttm_device *bdev, struct ttm_operation_ctx *ctx,
> >   			}
> >   		}
> >   	}
> > -	spin_unlock(&glob->lru_lock);
> > +	spin_unlock(&bdev->lru_lock);
> >   	return 0;
> >   }
> >   EXPORT_SYMBOL(ttm_device_swapout);
> > @@ -223,6 +221,7 @@ int ttm_device_init(struct ttm_device *bdev, struct ttm_device_funcs *funcs,
> >   
> >   	bdev->vma_manager = vma_manager;
> >   	INIT_DELAYED_WORK(&bdev->wq, ttm_device_delayed_workqueue);
> > +	spin_lock_init(&bdev->lru_lock);
> >   	INIT_LIST_HEAD(&bdev->ddestroy);
> >   	bdev->dev_mapping = mapping;
> >   	mutex_lock(&ttm_global_mutex);
> > @@ -235,7 +234,6 @@ EXPORT_SYMBOL(ttm_device_init);
> >   
> >   void ttm_device_fini(struct ttm_device *bdev)
> >   {
> > -	struct ttm_global *glob = &ttm_glob;
> >   	struct ttm_resource_manager *man;
> >   	unsigned i;
> >   
> > @@ -252,11 +250,11 @@ void ttm_device_fini(struct ttm_device *bdev)
> >   	if (ttm_bo_delayed_delete(bdev, true))
> >   		pr_debug("Delayed destroy list was clean\n");
> >   
> > -	spin_lock(&glob->lru_lock);
> > +	spin_lock(&bdev->lru_lock);
> >   	for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i)
> >   		if (list_empty(&man->lru[0]))
> >   			pr_debug("Swap list %d was clean\n", i);
> > -	spin_unlock(&glob->lru_lock);
> > +	spin_unlock(&bdev->lru_lock);
> >   
> >   	ttm_pool_fini(&bdev->pool);
> >   	ttm_global_release();
> > diff --git a/drivers/gpu/drm/ttm/ttm_execbuf_util.c b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
> > index 690ab97d52b7..071c48d672c6 100644
> > --- a/drivers/gpu/drm/ttm/ttm_execbuf_util.c
> > +++ b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
> > @@ -51,14 +51,12 @@ void ttm_eu_backoff_reservation(struct ww_acquire_ctx *ticket,
> >   	if (list_empty(list))
> >   		return;
> >   
> > -	spin_lock(&ttm_glob.lru_lock);
> >   	list_for_each_entry(entry, list, head) {
> >   		struct ttm_buffer_object *bo = entry->bo;
> >   
> > -		ttm_bo_move_to_lru_tail(bo, &bo->mem, NULL);
> > +		ttm_bo_move_to_lru_tail_unlocked(bo);
> >   		dma_resv_unlock(bo->base.resv);
> >   	}
> > -	spin_unlock(&ttm_glob.lru_lock);
> >   
> >   	if (ticket)
> >   		ww_acquire_fini(ticket);
> > @@ -154,7 +152,6 @@ void ttm_eu_fence_buffer_objects(struct ww_acquire_ctx *ticket,
> >   	if (list_empty(list))
> >   		return;
> >   
> > -	spin_lock(&ttm_glob.lru_lock);
> >   	list_for_each_entry(entry, list, head) {
> >   		struct ttm_buffer_object *bo = entry->bo;
> >   
> > @@ -162,10 +159,9 @@ void ttm_eu_fence_buffer_objects(struct ww_acquire_ctx *ticket,
> >   			dma_resv_add_shared_fence(bo->base.resv, fence);
> >   		else
> >   			dma_resv_add_excl_fence(bo->base.resv, fence);
> > -		ttm_bo_move_to_lru_tail(bo, &bo->mem, NULL);
> > +		ttm_bo_move_to_lru_tail_unlocked(bo);
> >   		dma_resv_unlock(bo->base.resv);
> >   	}
> > -	spin_unlock(&ttm_glob.lru_lock);
> >   	if (ticket)
> >   		ww_acquire_fini(ticket);
> >   }
> > diff --git a/drivers/gpu/drm/ttm/ttm_resource.c b/drivers/gpu/drm/ttm/ttm_resource.c
> > index ed1672a9f332..04f2eef653ab 100644
> > --- a/drivers/gpu/drm/ttm/ttm_resource.c
> > +++ b/drivers/gpu/drm/ttm/ttm_resource.c
> > @@ -91,7 +91,6 @@ int ttm_resource_manager_evict_all(struct ttm_device *bdev,
> >   		.no_wait_gpu = false,
> >   		.force_alloc = true
> >   	};
> > -	struct ttm_global *glob = &ttm_glob;
> >   	struct dma_fence *fence;
> >   	int ret;
> >   	unsigned i;
> > @@ -100,18 +99,18 @@ int ttm_resource_manager_evict_all(struct ttm_device *bdev,
> >   	 * Can't use standard list traversal since we're unlocking.
> >   	 */
> >   
> > -	spin_lock(&glob->lru_lock);
> > +	spin_lock(&bdev->lru_lock);
> >   	for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i) {
> >   		while (!list_empty(&man->lru[i])) {
> > -			spin_unlock(&glob->lru_lock);
> > +			spin_unlock(&bdev->lru_lock);
> >   			ret = ttm_mem_evict_first(bdev, man, NULL, &ctx,
> >   						  NULL);
> >   			if (ret)
> >   				return ret;
> > -			spin_lock(&glob->lru_lock);
> > +			spin_lock(&bdev->lru_lock);
> >   		}
> >   	}
> > -	spin_unlock(&glob->lru_lock);
> > +	spin_unlock(&bdev->lru_lock);
> >   
> >   	spin_lock(&man->move_lock);
> >   	fence = dma_fence_get(man->move);
> > diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
> > index d007feef7676..dbccac957f8f 100644
> > --- a/include/drm/ttm/ttm_bo_driver.h
> > +++ b/include/drm/ttm/ttm_bo_driver.h
> > @@ -180,9 +180,9 @@ static inline int ttm_bo_reserve_slowpath(struct ttm_buffer_object *bo,
> >   static inline void
> >   ttm_bo_move_to_lru_tail_unlocked(struct ttm_buffer_object *bo)
> >   {
> > -	spin_lock(&ttm_glob.lru_lock);
> > +	spin_lock(&bo->bdev->lru_lock);
> >   	ttm_bo_move_to_lru_tail(bo, &bo->mem, NULL);
> > -	spin_unlock(&ttm_glob.lru_lock);
> > +	spin_unlock(&bo->bdev->lru_lock);
> >   }
> >   
> >   static inline void ttm_bo_assign_mem(struct ttm_buffer_object *bo,
> > diff --git a/include/drm/ttm/ttm_device.h b/include/drm/ttm/ttm_device.h
> > index cda6efb4c34b..bae56d29e8ff 100644
> > --- a/include/drm/ttm/ttm_device.h
> > +++ b/include/drm/ttm/ttm_device.h
> > @@ -56,7 +56,6 @@ extern struct ttm_global {
> >   	 */
> >   
> >   	struct page *dummy_read_page;
> > -	spinlock_t lru_lock;
> >   
> >   	/**
> >   	 * Protected by ttm_global_mutex.
> > @@ -277,8 +276,9 @@ struct ttm_device {
> >   	struct ttm_pool pool;
> >   
> >   	/*
> > -	 * Protected by the global:lru lock.
> > +	 * Protection for the per manager LRU and ddestroy lists.
> >   	 */
> > +	spinlock_t lru_lock;
> >   	struct list_head ddestroy;
> >   
> >   	/*
> > --
> > 2.25.1

_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/dri-devel