cairo performance and poulsbo driver
Johan Bilien
jobi at via.ecp.fr
Wed Dec 16 01:59:35 PST 2009
Hi,
we are using the poulsbo driver which was written by TG for intel and is
basically a wrapper around some Xpsb binary blob.
One of our main problems nowadays is 2D performance. I have been using
the firefox-20090601 cairo trace as my benchmark, because our app is a
firefox based browser.
Running cairo master (and pixman 0.16.2), the image backend is about 3
times faster than the xlib one:
[ # ] backend test min(s) median(s) stddev.
[ 0] image firefox-20090601 110.229 119.423 4.00%
[ 0] xlib firefox-20090601 297.572 298.082 0.82%
So I thought that if I could make XRender use pixman instead of using
the driver I might be able to get closer to the image backend
performance.
I tried both disabling only the Composite hooks or all of exa's hooks,
but unfortunately I am still far from the image backend figures:
(Composite disabled)
[ # ] backend test min(s) median(s) stddev.count
[ 0] xlib firefox-20090601 269.082 269.082 0.00% 1/1
[ 0] image firefox-20090601 101.397 101.397 0.00% 1/1
(all EXA hooks disabled)
[ # ] backend test min(s) median(s) stddev.count
[ 0] xlib firefox-20090601 271.958 271.958 0.00% 1/1
[ 0] image firefox-20090601 100.829 100.829 0.00% 1/1
So I'm left wondering where the overhead of the xlib backend comes from.
If I run sysprof (profile attached) while running the trace (in the
Composite disabled case), I can see that pixman gets only 27.5% of the
CPU time, while 39.4% is spent "in kernel". I'm vaguely thinking that
these could be from moving pixmap data to and from the VRAM, but really
I have no idea.
Any idea on how to further investigate this?
Thanks
--
Johan Bilien
litl
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