Patch to avoid calling gettimeofday while busy-waiting (I830WaitLpRing)

[Carl Worth]

I noticed that I830WaitLpRing is making a system call to gettimeofday
while otherwise busy waiting.

Here's a patch to reduce that significantly, (calling gettimeofday
only every 4096 iterations). It doesn't actually improve performance
much as it primarily just makes the driver busy-wait faster. And all
the waiting appears to be due to the way the driver is written to
re-use the same in-video-memory state buffer for every composite
operation, (so no more than one can be in flight at a time).

I've put a lot more details on this and related issues here:

	http://www.cworth.org/exa/i965/synchronous_composite/

I'd greatly appreciate any feedback or suggestions for improving
things.

Thanks,

-Carl

-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-Elminate-gettimeofday-as-a-hotspot-in-I830WaitLpRing.patch
Type: application/octet-stream
Size: 2510 bytes
Desc: not available
URL: <http://lists.x.org/archives/xorg/attachments/20070710/46294d4f/attachment.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: not available
URL: <http://lists.x.org/archives/xorg/attachments/20070710/46294d4f/attachment.pgp>