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