XO 1.5 performance testing.

Jon Nettleton jon.nettleton at gmail.com
Mon Mar 14 03:28:40 EDT 2011

It has been a fun and fulfilling weekend tracking down performance
regressions when using DRI on the XO 1.5 platform.  One place I was
looking at specifically was blitting solids from userspace to the
kernel.  I found that copy_from_user was really chewing up a
significant amount of cpu.  Looking further I found that for VIA C7
processors these two options,  X86_INTEL_USERCOPY and
X86_USE_PPRO_CHECKSUM, are not enabled.

I have not done thorough testing on it, but after patch the kernel
with the attached patch my gtkperf run dropped from 63 seconds down to
50 seconds.  A 20% improvement is not bad, but more testing is
definitely needed, and testing both options independently is also
needed. I have my test kernel available here

If anyone else reports back that they are also seeing improvements I
will open a bug and we can track this improvement down further.

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