Re: [Intel-xe] [PATCH 2/5] drm/xe: Reduce the number list links in xe_vma

[Matthew Brost <matthew.brost@intel.com>]

On Thu, Jul 13, 2023 at 04:18:20PM -0400, Rodrigo Vivi wrote:
> On Tue, Jul 11, 2023 at 02:27:45PM -0700, Matthew Brost wrote:
> > Combine the userptr, rebind, and destroy links into a union as
> > the lists these links belong to are mutually exclusive.
> > 
> > v2: Adjust which lists are combined (Thomas H)
> > 
> > Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> > ---
> >  drivers/gpu/drm/xe/xe_bo.c       |  6 +++--
> >  drivers/gpu/drm/xe/xe_exec.c     |  2 +-
> >  drivers/gpu/drm/xe/xe_pt.c       |  2 +-
> >  drivers/gpu/drm/xe/xe_vm.c       | 45 ++++++++++++++++----------------
> >  drivers/gpu/drm/xe/xe_vm_types.h | 28 +++++++++-----------
> >  5 files changed, 41 insertions(+), 42 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
> > index 6353afa8d846..ca7f74ecb753 100644
> > --- a/drivers/gpu/drm/xe/xe_bo.c
> > +++ b/drivers/gpu/drm/xe/xe_bo.c
> > @@ -474,8 +474,10 @@ static int xe_bo_trigger_rebind(struct xe_device *xe, struct xe_bo *bo,
> >  			}
> >  
> >  			xe_vm_assert_held(vm);
> > -			if (list_empty(&vma->rebind_link) && vma->tile_present)
> > -				list_add_tail(&vma->rebind_link, &vm->rebind_list);
> > +			if (list_empty(&vma->combined_links.rebind) &&
> > +			    vma->tile_present)
> > +				list_add_tail(&vma->combined_links.rebind,
> > +					      &vm->rebind_list);
> >  
> >  			if (vm_resv_locked)
> >  				dma_resv_unlock(&vm->resv);
> > diff --git a/drivers/gpu/drm/xe/xe_exec.c b/drivers/gpu/drm/xe/xe_exec.c
> > index ba13d20ed348..bc5bd4bdc582 100644
> > --- a/drivers/gpu/drm/xe/xe_exec.c
> > +++ b/drivers/gpu/drm/xe/xe_exec.c
> > @@ -120,7 +120,7 @@ static int xe_exec_begin(struct xe_engine *e, struct ww_acquire_ctx *ww,
> >  	 * BOs have valid placements possibly moving an evicted BO back
> >  	 * to a location where the GPU can access it).
> >  	 */
> > -	list_for_each_entry(vma, &vm->rebind_list, rebind_link) {
> > +	list_for_each_entry(vma, &vm->rebind_list, combined_links.rebind) {
> >  		XE_WARN_ON(xe_vma_is_null(vma));
> >  
> >  		if (xe_vma_is_userptr(vma))
> > diff --git a/drivers/gpu/drm/xe/xe_pt.c b/drivers/gpu/drm/xe/xe_pt.c
> > index a8d96cbd53e3..3b43b32f4a33 100644
> > --- a/drivers/gpu/drm/xe/xe_pt.c
> > +++ b/drivers/gpu/drm/xe/xe_pt.c
> > @@ -1690,7 +1690,7 @@ __xe_pt_unbind_vma(struct xe_tile *tile, struct xe_vma *vma, struct xe_engine *e
> >  	}
> >  
> >  	if (!vma->tile_present)
> > -		list_del_init(&vma->rebind_link);
> > +		list_del_init(&vma->combined_links.rebind);
> >  
> >  	if (unbind_pt_update.locked) {
> >  		XE_WARN_ON(!xe_vma_is_userptr(vma));
> > diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> > index 5f4f6dab270a..b2847be6de6a 100644
> > --- a/drivers/gpu/drm/xe/xe_vm.c
> > +++ b/drivers/gpu/drm/xe/xe_vm.c
> > @@ -467,7 +467,8 @@ int xe_vm_lock_dma_resv(struct xe_vm *vm, struct ww_acquire_ctx *ww,
> >  
> >  		list_del_init(&vma->notifier.rebind_link);
> >  		if (vma->tile_present && !(vma->gpuva.flags & XE_VMA_DESTROYED))
> > -			list_move_tail(&vma->rebind_link, &vm->rebind_list);
> > +			list_move_tail(&vma->combined_links.rebind,
> > +				       &vm->rebind_list);
> >  	}
> >  	spin_unlock(&vm->notifier.list_lock);
> >  
> > @@ -608,7 +609,7 @@ static void preempt_rebind_work_func(struct work_struct *w)
> >  	if (err)
> >  		goto out_unlock;
> >  
> > -	list_for_each_entry(vma, &vm->rebind_list, rebind_link) {
> > +	list_for_each_entry(vma, &vm->rebind_list, combined_links.rebind) {
> >  		if (xe_vma_has_no_bo(vma) ||
> >  		    vma->gpuva.flags & XE_VMA_DESTROYED)
> >  			continue;
> > @@ -780,17 +781,20 @@ int xe_vm_userptr_pin(struct xe_vm *vm)
> >  	list_for_each_entry_safe(vma, next, &vm->userptr.invalidated,
> >  				 userptr.invalidate_link) {
> >  		list_del_init(&vma->userptr.invalidate_link);
> > -		list_move_tail(&vma->userptr_link, &vm->userptr.repin_list);
> > +		if (list_empty(&vma->combined_links.userptr))
> > +			list_move_tail(&vma->combined_links.userptr,
> > +				       &vm->userptr.repin_list);
> >  	}
> >  	spin_unlock(&vm->userptr.invalidated_lock);
> >  
> >  	/* Pin and move to temporary list */
> > -	list_for_each_entry_safe(vma, next, &vm->userptr.repin_list, userptr_link) {
> > +	list_for_each_entry_safe(vma, next, &vm->userptr.repin_list,
> > +				 combined_links.userptr) {
> >  		err = xe_vma_userptr_pin_pages(vma);
> >  		if (err < 0)
> >  			goto out_err;
> >  
> > -		list_move_tail(&vma->userptr_link, &tmp_evict);
> > +		list_move_tail(&vma->combined_links.userptr, &tmp_evict);
> >  	}
> >  
> >  	/* Take lock and move to rebind_list for rebinding. */
> > @@ -798,10 +802,8 @@ int xe_vm_userptr_pin(struct xe_vm *vm)
> >  	if (err)
> >  		goto out_err;
> >  
> > -	list_for_each_entry_safe(vma, next, &tmp_evict, userptr_link) {
> > -		list_del_init(&vma->userptr_link);
> > -		list_move_tail(&vma->rebind_link, &vm->rebind_list);
> > -	}
> > +	list_for_each_entry_safe(vma, next, &tmp_evict, combined_links.userptr)
> > +		list_move_tail(&vma->combined_links.rebind, &vm->rebind_list);
> >  
> >  	dma_resv_unlock(&vm->resv);
> >  
> > @@ -845,10 +847,11 @@ struct dma_fence *xe_vm_rebind(struct xe_vm *vm, bool rebind_worker)
> >  		return NULL;
> >  
> >  	xe_vm_assert_held(vm);
> > -	list_for_each_entry_safe(vma, next, &vm->rebind_list, rebind_link) {
> > +	list_for_each_entry_safe(vma, next, &vm->rebind_list,
> > +				 combined_links.rebind) {
> >  		XE_WARN_ON(!vma->tile_present);
> >  
> > -		list_del_init(&vma->rebind_link);
> > +		list_del_init(&vma->combined_links.rebind);
> >  		dma_fence_put(fence);
> >  		if (rebind_worker)
> >  			trace_xe_vma_rebind_worker(vma);
> > @@ -883,9 +886,7 @@ static struct xe_vma *xe_vma_create(struct xe_vm *vm,
> >  		return vma;
> >  	}
> >  
> > -	INIT_LIST_HEAD(&vma->rebind_link);
> > -	INIT_LIST_HEAD(&vma->unbind_link);
> > -	INIT_LIST_HEAD(&vma->userptr_link);
> > +	INIT_LIST_HEAD(&vma->combined_links.rebind);
> >  	INIT_LIST_HEAD(&vma->userptr.invalidate_link);
> >  	INIT_LIST_HEAD(&vma->notifier.rebind_link);
> >  	INIT_LIST_HEAD(&vma->extobj.link);
> > @@ -1058,15 +1059,14 @@ static void xe_vma_destroy(struct xe_vma *vma, struct dma_fence *fence)
> >  	struct xe_vm *vm = xe_vma_vm(vma);
> >  
> >  	lockdep_assert_held_write(&vm->lock);
> > -	XE_BUG_ON(!list_empty(&vma->unbind_link));
> > +	XE_BUG_ON(!list_empty(&vma->combined_links.destroy));
> >  
> >  	if (xe_vma_is_userptr(vma)) {
> >  		XE_WARN_ON(!(vma->gpuva.flags & XE_VMA_DESTROYED));
> >  
> >  		spin_lock(&vm->userptr.invalidated_lock);
> > -		list_del_init(&vma->userptr.invalidate_link);

This doesn't, will remove.

> > +		list_del(&vma->userptr.invalidate_link);
> >  		spin_unlock(&vm->userptr.invalidated_lock);
> > -		list_del(&vma->userptr_link);

This does.

Matt

> 
> this chunk has nothing to do with the combined_links, so it needs a separated patch.
> 
> >  	} else if (!xe_vma_is_null(vma)) {
> >  		xe_bo_assert_held(xe_vma_bo(vma));
> >  
> > @@ -1087,9 +1087,6 @@ static void xe_vma_destroy(struct xe_vma *vma, struct dma_fence *fence)
> >  	}
> >  
> >  	xe_vm_assert_held(vm);
> > -	if (!list_empty(&vma->rebind_link))
> > -		list_del(&vma->rebind_link);
> > -
> >  	if (fence) {
> >  		int ret = dma_fence_add_callback(fence, &vma->destroy_cb,
> >  						 vma_destroy_cb);
> > @@ -1443,11 +1440,12 @@ void xe_vm_close_and_put(struct xe_vm *vm)
> >  
> >  		/* easy case, remove from VMA? */
> >  		if (xe_vma_has_no_bo(vma) || xe_vma_bo(vma)->vm) {
> > +			list_del_init(&vma->combined_links.rebind);
> >  			xe_vma_destroy(vma, NULL);
> >  			continue;
> >  		}
> >  
> > -		list_add_tail(&vma->unbind_link, &contested);
> > +		list_move_tail(&vma->combined_links.destroy, &contested);
> >  	}
> >  
> >  	/*
> > @@ -1475,8 +1473,9 @@ void xe_vm_close_and_put(struct xe_vm *vm)
> >  	 * Since we hold a refcount to the bo, we can remove and free
> >  	 * the members safely without locking.
> >  	 */
> > -	list_for_each_entry_safe(vma, next_vma, &contested, unbind_link) {
> > -		list_del_init(&vma->unbind_link);
> > +	list_for_each_entry_safe(vma, next_vma, &contested,
> > +				 combined_links.destroy) {
> > +		list_del_init(&vma->combined_links.destroy);
> >  		xe_vma_destroy_unlocked(vma);
> >  	}
> >  
> > diff --git a/drivers/gpu/drm/xe/xe_vm_types.h b/drivers/gpu/drm/xe/xe_vm_types.h
> > index f17dc5d7370e..84bf1620214c 100644
> > --- a/drivers/gpu/drm/xe/xe_vm_types.h
> > +++ b/drivers/gpu/drm/xe/xe_vm_types.h
> > @@ -49,21 +49,19 @@ struct xe_vma {
> >  	 */
> >  	u64 tile_present;
> >  
> > -	/** @userptr_link: link into VM repin list if userptr */
> > -	struct list_head userptr_link;
> > -
> > -	/**
> > -	 * @rebind_link: link into VM if this VMA needs rebinding, and
> > -	 * if it's a bo (not userptr) needs validation after a possible
> > -	 * eviction. Protected by the vm's resv lock.
> > -	 */
> > -	struct list_head rebind_link;
> > -
> > -	/**
> > -	 * @unbind_link: link or list head if an unbind of multiple VMAs, in
> > -	 * single unbind op, is being done.
> > -	 */
> > -	struct list_head unbind_link;
> > +	/** @combined_links: links into lists which are mutually exclusive */
> > +	union {
> > +		/** @userptr: link into VM repin list if userptr */
> > +		struct list_head userptr;
> > +		/**
> > +		 * @rebind: link into VM if this VMA needs rebinding, and
> > +		 * if it's a bo (not userptr) needs validation after a possible
> > +		 * eviction. Protected by the vm's resv lock.
> > +		 */
> > +		struct list_head rebind;
> > +		/** @destroy: link to contested list when VM is being closed */
> > +		struct list_head destroy;
> > +	} combined_links;
> 
> this is a good optimization, but from the organization point of view and naming
> this is getting confused... if we could at least find a generic name that makes
> sense for these mutual exclusive operations other then 'combined_links'.... :/
> 
> but well, I'm also not good with names.
> 
> with separated patches,
> 
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> on both...
> 
> >  
> >  	/** @destroy_cb: callback to destroy VMA when unbind job is done */
> >  	struct dma_fence_cb destroy_cb;
> > -- 
> > 2.34.1
> >