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. Cheers, Thomas. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
