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

[Christian König <ckoenig.leichtzumerken@xxxxxxxxx>]

Am 16.03.21 um 10:35 schrieb Daniel Vetter:
> On Mon, Mar 15, 2021 at 05:04:22PM +0100, Christian König wrote:
> > Instead of having a global lock.
> >
> > Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> I guess per zone lru lock is a lot more work since then we need to handle
> ordering and ABBA deadlocks? s/zone/mem region/ I think is the proper ttm
> lingo.

Making the LRU per resource manager is the long term goal, yes.

My key idea so far is that we make bo->mem a pointer and then move the 
LRU handling into the resource object instead of the BO.

The resource object then just references the BO and so that we can 
figure out which BO to evict or which fence to wait for to free up a 
resource.

Regards,
Christian.

> -Daniel
>
> > ---
> >   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);
> >   		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 a1be88be357b..a8103c8718a3 100644
> > --- a/drivers/gpu/drm/ttm/ttm_bo.c
> > +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> > @@ -242,9 +242,9 @@ 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;
> > @@ -303,7 +303,7 @@ 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);
> > @@ -313,7 +313,7 @@ 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,
> > @@ -323,7 +323,7 @@ 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;
> > @@ -332,13 +332,13 @@ 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)
> > @@ -355,13 +355,12 @@ 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;
> >   
> > @@ -372,24 +371,24 @@ 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;
> >   }
> > @@ -424,7 +423,7 @@ 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
> > @@ -438,17 +437,17 @@ 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);
> > @@ -622,7 +621,7 @@ 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;
> > @@ -659,7 +658,7 @@ 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);
> > @@ -673,7 +672,7 @@ 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)
> > @@ -773,10 +772,9 @@ 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;
> >   }
> >   
> > @@ -1160,7 +1158,6 @@ 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;
> >   
> > @@ -1185,7 +1182,7 @@ 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 2c280fb1e992..924d892109e8 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

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