[RFC] [PATCH 1/2] Add a basic support of logging cpu and gpu time

Eric Anholt eric at anholt.net
Wed Aug 24 14:48:31 PDT 2011


On Wed, 24 Aug 2011 10:08:01 +0800, Yuanhan Liu <yuanhan.liu at intel.com> wrote:
> Restructured to match the latest master branch. The implementation is 
> quite ugly and dirty. But it didn't change the structure of the trace file.
> 
> --
> From ec52fd63c08eca86fca42ae27e79309130984078 Mon Sep 17 00:00:00 2001
> From: Liu Aleaxander <Aleaxander at gmail.com>
> Date: Wed, 24 Aug 2011 09:55:03 +0800
> Subject: [PATCH 1/2] Add a basic support of logging cpu and gpu time
> 
> Logging GPU time is a kind of trick, since you can't get the gpu time
> immediately after your opengl call. Thus we need to move it at the end of
> frame to reduce the time query overhead.
> 
> Well, that would introduce another problem, as the trace_writer doesn't
> know the real opengl call for the specified gpu time. Thus I introduce
> another log file for time. Please see comments inline for more info.

Trace capture time seems like the wrong time to be doing performance
analysis to me.  I would expect GPU performance analysis to be done
after the fact in qapitrace.  Then you could do multiple runs to ensure
reliable data, and you could do even more clever things like culling all
primitives to try to determine the balance of time used between VS and
FS.
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