[PATCH] Avoid an unwanted pixmap migration in EXA when compositing trapezoids

[Bernardo Innocenti]

Fredrik Höglund wrote:

> This patch solves the trapezoid migration problem Michel Dänzer described
> in a recent email on this mailing list.

Thank you, we were looking exactly for an improvement in this area!

FYI, aleph tested your patch on the OLPC and posted his results on
the devel@ mailing-list:

-------- Original Message --------
Subject: Re: X trapezoids rendering performance
Date: Wed, 22 Aug 2007 01:53:34 +0200
From: Stefano Fedrigo <aleph at develer.com>
To: Bernardo Innocenti <bernie at codewiz.org>
CC: OLPC Development <devel at lists.laptop.org>,  Jordan Crouse <jordan.crouse at amd.com>, Jim Gettys <jg at laptop.org>
References: <46C90EDD.8020805 at codewiz.org>

Bernardo Innocenti wrote:
 > This patch is likely to make a big difference in the EXA codepath
 > I benchmarked, which is heavily used by the OLPC GTK theme.
 >
 > The mini-benchmark attached to #1837 mimics it by drawing rounded
 > edges shapes with Cairo.
 > [...]
 > -------- Original Message --------
 > Subject: [PATCH] Avoid an unwanted pixmap migration in EXA when
 > compositing trapezoids
 > Date: Wed, 15 Aug 2007 19:58:56 +0200
 > From: Fredrik Höglund <fredrik at kde.org>

I made quite some testing with the attached benchmark: I tried with a few
different configurations (24 and 16 bit display, different snapshots of
xserver 1.4): speed increase is consistently at 30%.
Definitely not bad, and the patch is already committed in the server-1.4-branch.
Looking at oprofile output is evident that the main optimization is avoiding
memcpy'ing the pixmaps.

Benchmark result without the patch (16 bpp):
   op: rect
user: 2.600
  sys: 0.050
real: 7.930
op/s: 126.103

Oprofile report:

   samples|      %|
------------------
       534 56.8085 Xorg
	          TIMER:0|
	  samples|      %|
	------------------
	      243 45.5056 libc-2.6.so
	      211 39.5131 libpixman-1.so.0.9.4
	       38  7.1161 amd_drv.so
	       17  3.1835 libexa.so
	       16  2.9963 Xorg
	        8  1.4981 libfb.so
	        1  0.1873 libextmod.so
	[...]

samples  %        linenr info                 image name               app name      symbol name
225      23.9362  (no location information)   libc-2.6.so              Xorg          memcpy
213      22.6596  (no location information)   libcairo.so.2.11.5       python        (no symbols)
168      17.8723  pixman-edge.c:322           libpixman-1.so.0.9.4     Xorg          pixman_rasterize_edges
63        6.7021  (no location information)   no-vmlinux               no-vmlinux    (no symbols)
56        5.9574  (no location information)   libpython2.5.so.1.0      python        (no symbols)
19        2.0213  cim_gp.c:3305               amd_drv.so               Xorg          gp_wait_until_idle
16        1.7021  (no location information)   libc-2.6.so              python        msort_with_tmp
12        1.2766  pixman-mmx.c:0              libpixman-1.so.0.9.4     Xorg          __divdi3
11        1.1702  cim_gp.c:1228               amd_drv.so               Xorg          gp_color_bitmap_to_screen_blt


** With the patch applied:

   op: rect
user: 2.550
  sys: 0.020
real: 6.070
op/s: 164.745

   samples|      %|
------------------
       709 47.1096 Xorg
                   TIMER:0|
           samples|      %|
         ------------------
               511 72.0733 libpixman-1.so.0.9.4
                71 10.0141 amd_drv.so
                43  6.0649 Xorg
                40  5.6417 libexa.so
                36  5.0776 libc-2.6.so
                 7  0.9873 libfb.so
                 1  0.1410 librt-2.6.so
	[...]

samples  %      linenr info                 image name               app name     symbol name
407    27.0432  (no location information)   libcairo.so.2.11.5       python       (no symbols)
322    21.3953  pixman-edge.c:322           libpixman-1.so.0.9.4     Xorg         pixman_rasterize_edges
130     8.6379  (no location information)   no-vmlinux               no-vmlinux   (no symbols)
103     6.8439  (no location information)   libpython2.5.so.1.0      python       (no symbols)
90      5.9801  pixman-utils.c:165          libpixman-1.so.0.9.4     Xorg         pixman_fill
40      2.6578  (no location information)   libc-2.6.so              python       msort_with_tmp
32      2.1262  cim_gp.c:1228               amd_drv.so               Xorg         gp_color_bitmap_to_screen_blt


-- 
   // Bernardo Innocenti
 \X/  http://www.codewiz.org/