On optimizing Theora

[Tiago Marques]

Hi,

Can you please try both options with also the following
ones:*-ftree-vectorize -funroll-loops -m3dnow
*

Also, it may be a good idea to test both geode and i586 with *-m3dnow *and *
-mno3dnow*, since the compiler may be causing problems while vectorizing.
Another option is to test also with i486 compilations, as per what I had
already found in this thread:

http://geode.insideo.net/info-linux_archives/msg00396.html

Let me underscore my colleague's statement.  Do not use the 586 target.
In testing we've found that the 586 "optimized" version can be up to 3x
slower vs. the 386/486 versions on the Geode LX.


This should be due to Geode LX not being a superscalar processor (while the
i586 is) may be causing problems even with the i586 march.

Best regards,
                          Tiago Marques



On Fri, Feb 20, 2009 at 2:23 PM, Benjamin M. Schwartz <
bmschwar at fas.harvard.edu> wrote:

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> Tomeu Vizoso wrote:
> > On Fri, Feb 20, 2009 at 06:41,  <quozl at laptop.org> wrote:
> >> On Fri, Feb 20, 2009 at 12:28:42AM -0500, Benjamin M. Schwartz wrote:
> >>> GCC 4.3 evidently does not do a very good job of optimizing for geode.
> >> What percentage of CPU time was spent in libtheora?
>
> 100%.  The encoder was operating in a continuous loop.
>
> > Yeah, both X and jffs2 seem to use a lot of cpu on the XO, so if they
> > were involved during your tests, you may have seen little of theora
> > itself.
>
> Neither X nor jffs2 was involved.  The input file (y4m or ogv) was cached
> in memory, and the output stream (ogv or y4m) was being sent directly to
> /dev/null, and not displayed.
>
> The only action being taken in X was to display, in the Terminal activity,
> a text-only progress bar, rendered by the encoder_example, or dump_video
> command.  These commands are part of libtheora, and were recompiled with
> it, so the point remains.
>
> - --Ben
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