Why The Radeon Gallium3D Performance Is Down

[phoronix]

Phoronix: Why The Radeon Gallium3D Performance Is Down

After yesterday's article about the Grinch that stole the Radeon Gallium3D performance, here's three offending commits since Mesa 7.10 that are causing the open-source Radeon Gallium3D driver to run slower than it should.

http://www.phoronix.com/vr.php?view=16875

[curaga]

Very nice, Michael! Enjoy your beer

[kobblestown]

Good job, Michael! I hope your detective work helps to rectify the problem.

During the holidays I plan to use the PTS for the first time to see how it works for me. But it's obvious it is of great use to the Linux community.

Happy holidays, everyone!

[chrisr]

It's not like any of those commits have already been found to be broken, is it.

Oh, wait...

[r300g] Flickering user interface in WoW

Raised back in October and bisected to 363ff844753c46ac9c13866627e096b091ea81f8.

Can we please now revert this? How much more damage does it need to cause!?

[przemoli]

Such articles reminds me to disable ABP on phoronix.com!!

Well deserved beer!

(only thing that is missing, is info about notifing proper mesa developers about your findings, but I guess they read Phoronix regularly anyway)

[stalkerg]

Thaks Michael!!! Good job.
I hope to Marek...

[AnonymousCoward]

(only thing that is missing, is info about notifing proper mesa developers about your findings, but I guess they read Phoronix regularly anyway)

If there's no real bugreport and just this article, I can only guess the level of annoyance this causes them, expecially when random "helpful" people also point them at it.

[Sidicas]

Reasons for moving to winsys:
http://lists.freedesktop.org/archive...st/010263.html

It looks like it was expected to see a 0-15% performance boost, but because GEM_WAIT was disabled, it ended up becoming a performance regression..
Disabing GEM_WAIT is probably temporary, so it's probably nothing to really worry about.

On a side note, the Gallium drivers have in the past needed more CPU usage to hit the higher framerates than the Catalyst drivers did.. So fixes like this that reduce overhead gets me all excited.

[marek]

chrisr, it is reverted in this branch, which I will push soon:
git://people.freedesktop.org/~mareko/mesa radeon-perf-fix
It fixes the performance regression in Nexuiz and hopefully even the bug you reported.

Sidicas, the performance improvement is unrelated to the regression in r300g. The regression is caused by a commit that's merely a cleanup.

Michael, thanks for doing this. The commit "winsys/radeon: move GEM domains out of the drivers into winsys" will be reverted, fixing Nexuiz.
The commit "r300g: implement fences using dummy relocations" won't be reverted. It properly implements glFinish(), which is used by openarena to eliminate the input lag. It's important for playability of the game.

[gururise]

Thank you Michael for a well written, very informative article!!!