[cairo] Performance of the refactored Pixman

Soeren Sandmann sandmann at daimi.au.dk
Wed Jun 17 05:03:42 PDT 2009


> The patch to achieve this will be pretty damn huge, mind - but I think
> it removes more lines of code than it adds, overall.  The API entry
> points remain unchanged (hey, it still has to interface with Xorg), but
> the new structure is filled immediately and used thereafter.

Yes, the total patch to achieve this will be huge, but I think it can
be broken down into smaller self-contained commits that can be applied

I would encourage you to spend some time getting familiar with git,
then publish a repository containing the code you are working on. That
way, we get meaningful, bisectable commits and it should be easier for
you to deal with the inevitable conflicts.

> I'm also seeing a very large regression on glyph rendering, though.
> It could be just an oversight on my part (it looks like it's using
> the generic code path for some reason), so I'll debug it.  In any
> case I'll have to extend the coverage to the MMX, SSE and Altivec
> backends - so far I've only done the ARM ones.

We need benchmarks that are quantiable and reproducable. I am going to
ignore any further claims about "very large regression" and "40% of
the performance" unless they are backed by benchmarks that:

        - don't depend on X

        - run at enough iterations that their results are believable

        - have published source code, preferably in the pixman/test

The cairo performance test suite when run with CAIRO_TEST_TARGET=image
can be used for this, but stand-alone benchmarks are also welcome.

A real performance test suite like cairo's would be welcome of course,
but the above is the minimum needed for a useful benchmark.


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