On Wed, Jan 08, 2014 at 04:57:52PM +0100, Thomas Richter wrote: > Hi folks, > > during the changes from 3.12rc7 to 3.13rc4, the performance of > XDrawRectangles() dropped considerably. Interestingly, it is not the > raw rectangles drawing operations that are slow, but it seems that > the "per-call" overhead has increased by one magnitude. In specific, > if you use the unmodified "x11pref" program: > > x11pref -rect10 > > no substiantial changes are visible. However, if the rectangles are > drawn one by one by changing: > > /* snip: old version, lines 86ff of do_rects.c of the x11perf program */ > > void > DoRectangles(XParms xp, Parms p, int reps) > { > int i; > > for (i = 0; i != reps; i++) { > XFillRectangles(xp->d, xp->w, pgc, rects, p->objects); > if (pgc == xp->bggc) > pgc = xp->fggc; > else > pgc = xp->bggc; > CheckAbort (); > } > } > > /* to the following : */ > > void > DoRectangles(XParms xp, Parms p, int reps) > { > int i; > int j; > > for (i = 0; i != reps; i++) { > for(j = 0;j < p->objects;j++) { > XFillRectangles(xp->d, xp->w, pgc, rects+j, 1); > } > if (pgc == xp->bggc) > pgc = xp->fggc; > else > pgc = xp->bggc; > CheckAbort (); > } > } > > by instead drawing the rectangles one by one, the performance is > decreased to one eigths of the original performance: > > 400000 trep @ 0.0687 msec ( 14600.0/sec): 10x10 rectangle (new) > 2500000 trep @ 0.0107 msec ( 93900.0/sec): 10x10 rectangle (old) > > Thus, apparently, not the actual hardware acceleration degraded, but > there is something in the call path that slowed down the call > considerably. > > Any idea what changed? If the ddx is indeed the same and Chris doesn't have any ideas I guess a full bisect of the kernel should help a lot. Could very well be that some seemingly unrelated change in e.g. the scheduler caused havoc ... -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx