On Wed, Jul 15, 2015 at 03:58:33PM +0000, Daniel, Thomas wrote: > > -----Original Message----- > > From: Chris Wilson [mailto:chris@xxxxxxxxxxxxxxxxxx] > > Sent: Wednesday, July 15, 2015 4:47 PM > > To: Daniel, Thomas > > Cc: Goel, Akash; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Belgaumkar, Vinay; Winiarski, > > Michal; Zou, Nanhai > > Subject: Re: [PATCH v4] drm/i915: Add soft-pinning API for execbuffer > > > > On Wed, Jul 15, 2015 at 03:41:49PM +0000, Daniel, Thomas wrote: > > > > -----Original Message----- > > > > From: Chris Wilson [mailto:chris@xxxxxxxxxxxxxxxxxx] > > > > Sent: Wednesday, July 15, 2015 4:06 PM > > > > To: Goel, Akash > > > > Cc: Daniel, Thomas; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Belgaumkar, Vinay; > > > > Winiarski, Michal; Zou, Nanhai > > > > Subject: Re: [PATCH v4] drm/i915: Add soft-pinning API for execbuffer > > > > > > > > On Wed, Jul 15, 2015 at 08:25:23PM +0530, Goel, Akash wrote: > > > > > >>+int > > > > > >>+i915_gem_evict_for_vma(struct i915_vma *target) > > > > > >>+{ > > > > > >>+ struct drm_mm_node *node, *next; > > > > > >>+ > > > > > >>+ list_for_each_entry_safe(node, next, > > > > > >>+ &target->vm->mm.head_node.node_list, > > > > > >>+ node_list) { > > > > > >>+ struct i915_vma *vma; > > > > > >>+ int ret; > > > > > >>+ > > > > > >>+ if (node->start + node->size <= target->node.start) > > > > > >>+ continue; > > > > > >>+ if (node->start >= target->node.start + target- > > >node.size) > > > > > >>+ break; > > > > > >>+ > > > > > >>+ vma = container_of(node, typeof(*vma), node); > > > > > >>+ > > > > > >>+ if (vma->pin_count) { > > > > > >>+ /* We may need to evict a buffer in the same > > batch */ > > > > > >>+ if (!vma->exec_entry) > > > > > >>+ return -EBUSY; > > > > > >>+ > > > > > >>+ if (vma->exec_entry->flags & > > EXEC_OBJECT_PINNED) > > > > > >>+ /* Overlapping fixed objects in the > > same batch > > > > > >>*/ > > > > > >>+ return -EINVAL; > > > > > >>+ > > > > > >>+ return -ENOSPC; > > > > > > > > > > Can we actually hit this condition, considering the soft pinned > > > > > objects are now on the front side of 'eb->vmas' list ? > > > > > If we do encounter such a case, it probably means that the > > > > > overlapping object is already pinned from some other path. > > > > > > > > Note that softpinned objects are only first on the second pass through > > > > the reservation. > > > Eh? I modified i915_gem_execbuffer_reserve() to always put the softpinned > > vmas first so they should never collide with objects in the same execbuff. > > > > That would be a severe performance penalty for the usual case where we > > only have to run once through the list. > How so? execbuffer_reserve() already traverses the entire vma list and does a list_move or list_move_tail onto ordered_vmas for each entry. I've simply created a new list for the softpinned vmas and spliced the two together at the end. I posted the fix for that a few months ago. > > > This contains special stuff which I don't have visibility of (mm.interval_tree, > > vma.active). > > > > Yes. I mentioned that using softpin introduced some perf regressions. > > -Chris > Can we get your improvements as follow-up patches? No. Softpin has requirements that are not met by the current kernel. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
