On Fri, Oct 16, 2015 at 08:54:20AM +0000, Daniel, Thomas wrote: > Hi, > > > -----Original Message----- > > From: Intel-gfx [mailto:intel-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of > > David Herrmann > > Sent: Wednesday, October 7, 2015 11:23 AM > > To: Chris Wilson; Daniel Vetter; Intel Graphics Development; dri- > > devel@xxxxxxxxxxxxxxxxxxxxx > > Subject: Re: [Intel-gfx] [PATCH 1/3] drm: Track drm_mm nodes with an interval > > tree > > > > Hi > > > > On Tue, Oct 6, 2015 at 1:19 PM, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote: > > > On Tue, Oct 06, 2015 at 01:11:56PM +0200, Daniel Vetter wrote: > > >> On Tue, Oct 06, 2015 at 11:53:09AM +0100, Chris Wilson wrote: > > >> > In addition to the last-in/first-out stack for accessing drm_mm nodes, > > >> > we occasionally and in the future often want to find a drm_mm_node by an > > >> > address. To do so efficiently we need to track the nodes in an interval > > >> > tree - lookups for a particular address will then be O(lg(N)), where N > > >> > is the number of nodes in the range manager as opposed to O(N). > > >> > Insertion however gains an extra O(lg(N)) step for all nodes > > >> > irrespective of whether the interval tree is in use. For future i915 > > >> > patches, eliminating the linear walk is a significant improvement. > > >> > > > >> > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > >> > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx > > >> > > >> For the vma manager David Herrman put the interval tree outside of > > drm_mm. > > >> Whichever way we pick, but I think we should be consistent about this. > > > > > > Given that the basis of this patch is that functionality exposed by > > > drm_mm (i.e. drm_mm_reserve_node) is too slow for our use case (i.e. > > > there is a measurable perf degradation if we switch over from the mru > > > stack to using fixed addresses) it makes sense to improve that > > > functionality. The question is then why the drm_vma_manager didn't use > > > and improve the existing functionality... > > > > I didn't want to slow down drm_mm operations, so I kept it separate. I > > don't mind if it is merged into drm_mm. It'd be trivial to make the > > vma-manager use it (only on the top-level, though). > > > > Thanks > > David > > Is there a conclusion to this discussion? I'm under increasing pressure to get the i915 soft-pinning merged and Chris's latest version depends on this interval tree. > > I've been told to post a new rebase of the version which doesn't use the interval tree if not. In my opiniong pushing the interval tree into drm_mm.c makes tons of sense, so that we don't have to duplicate this between i915 and the vma manager. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
