On Wed, May 19, 2010 at 09:51:33PM +0200, Thomas Hellström wrote: > Daniel, > TTM releases the spinlock protecting the drm_mm manager in between > evictions to be able to wait (without holding locks) for bo idle. > That means that the lru list may have changed between the first > eviction and the next. In practice, drivers either don't allow > simultaneous bo validation or should disallow it if thrashing is > likely to occur, so the likelyhood of the lru list changing in > between evictions should be small but it needs to be taken into > account. Well, in my opinion ttm locking optimize for the wrong case: Usually there should be a little bit of room free to fully pipeline everything. And if it there is no room free anymore, performance is gonna dip anyway, so we might as well block. I think the linux vm with the split between asynchronous background writeback and synchronous writeback in case of low amounts of free memory could be used as inspiration. Whatever, I think ttm could use this fair eviction stuff even with the current locking scheme: Do all the accounting under the spinlock, i.e. - scanning the lru - building up the eviction list - mark the memory blocks as free (with drm_mm_put_block) - reserve the complete free hole (needs a new function in drm_mm, but range-restricted allocations are not yet implemented yet, anyway) with a temporary object. Then do the effective eviction outside the spinlock. iirc ttm already uses such shadow (dunno what they're really called) objects for buffer moves. > Nevertheless, the drm_mm.c cleanup is > Acked-by: Thomas Hellstrom <thellstrom@xxxxxxxxxx> Does that include the drm_mm_node->private pointer removal? Jerome naked that one (but I've objected). Just to clarify. > I'll leave it to the Intel guys to comment on the fair eviction stuff. > > /Thomas Thanks, Daniel -- Daniel Vetter Mail: daniel@xxxxxxxx Mobile: +41 (0)79 365 57 48 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
