[PATCH] Implement support for GPU timings of calls when proofiling with glretrace.

[Eric Anholt]

José Fonseca <jose.r.fonseca at gmail.com> writes:

> Hi Carl,
>
> Your patch indeed addresses most of the issues I had with the original
> timer query patches.
>
> Alas I recently asked James Benton, an intern at VMware, to start
> looking at this:
>
>   https://github.com/exjam/apitrace
>
> It's unfortunate this effort duplication.  At a glance, I think his
> effort is a bit ahead:
> - it keeps.a ceiling on maximum number on queries open

Seems like you should be able to be totally asynchronous, and not need
to worry about any limits on queries.  You're going to get throttled at
some frame boundaries at least, so periodically a ton of old queries get
finished and you can reap them.

> - keeps track of bound shader (and there's a script that can aggregate
> gpu times per shader, whic means one can see the shader that takes
> most gpu total)

Thanks!  I've been needing this feature for *ages*.

The issue I have right now with trying to do performance debug through
apitrace is I can't easily assign blame between the VS and FS of the
shader program that's taking all the GPU time.

Hopefully at some point we get performance counters hooked up to more
easily answer that question, but for now to figure that out, I've been
trying to go into the trace and whack the FS source to just be
gl_FragData[0] = vec4(0, 1, 0, 0) (and updating the length argument in
the API call -- would be nice for that to be automatic).  An edited
trace appears in /tmp, which fails under apitrace dump or qapitrace
with:

error: (glShaderSourceARB) unknown call detail 3

so I can't quite answer my question yet.

As an aside, this edit makes qapitrace suck up 10g of memory and writes
a new 1.2gb trace to disk over the course of a few minutes.  It would be
nice if trace edits could be expressed in some small files as diffs to
an original file.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 197 bytes
Desc: not available
URL: <http://lists.freedesktop.org/archives/apitrace/attachments/20120801/ceff1f69/attachment.pgp>