Intel 945 backtrace

[Eric Anholt]

On Wed, 2008-12-31 at 18:40 +0000, Peter Clifton wrote:
> Hi guys,
> 
> I've been testing the beta release of the 2.6 series Intel driver
> against a 2.6.28 kernel, with UXA and DRI2 enabled.
> 
> (I had 'Option "DRI2" "off"' in the Xorg.conf, but apparently that was
> ignored - perhaps I put it in the wrong place, or this is not the right
> option to control DRI2).
> 
> I've been noticing really poor performance whilst rendering lots of
> small lines, something which x11perf -line10 seems to bear out:
> 
> 
> x11perf - X11 performance program, version 1.2
> The X.Org Foundation server version 10599003 on :0.0
> from pcjc2lap
> Wed Dec 31 18:36:35 2008
> 
> Sync time adjustment is 0.0708 msecs.
> 
>  600000 reps @   0.0100 msec (100000.0/sec): 10-pixel line
>  600000 reps @   0.0100 msec (100000.0/sec): 10-pixel line
>  600000 reps @   0.0100 msec (100000.0/sec): 10-pixel line
>  600000 reps @   0.0100 msec (100000.0/sec): 10-pixel line
>  600000 reps @   0.0100 msec ( 99900.0/sec): 10-pixel line
> 3000000 trep @   0.0100 msec (100000.0/sec): 10-pixel line
> 
> 
> When profiling, it appears the hot-spot is in the kernel, with ~90% of
> total system time spent waiting in there.
> 
> I upgraded to a git version of sysprof today, and this is able to trace
> further inside the kernel. Hopefully this debugging information will be
> of use (I can send the whole capture file to anyone who wants it).
> 
> This was traced whilst running x11perf -line10. The timings above were
> recorded without sysprof tracing, in case the sysprof overhead skewed
> the timings.

Thanks for the sysprof data.  The fix for software fallback performance
just got merged to the stable branch, so that should fix this problem in
the next rc.

-- 
Eric Anholt
eric at anholt.net                         eric.anholt at intel.com


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