Re: [patch] CFS scheduler, -v12

William Lee Irwin III
2007-05-18T04:13:00Z

On Sun, May 13, 2007 at 05:38:53PM +0200, Ingo Molnar wrote:
>> So i've added a yield workaround to -v12, which makes it work similar to
>> how the vanilla scheduler and SD does it. (Xorg has been notified and
>> this bug should be fixed there too. This took some time to debug because
>> the 3D driver i'm using for testing does not use sys_sched_yield().) The
>> workaround is activated by default so -v12 should work 'out of the box'.

On Thu, May 17, 2007 at 05:18:41PM -0700, Bill Huey wrote:
> This is an incorrect analysis. OpenGL has the ability to "yield" after
> every frame specifically for SGI IRIX (React/Pro) frame scheduler (driven
> by the system vertical retrace interrupt) so that it can free up CPU
> resources for other tasks to run. The problem here is that the yield
> behavior is treated generally instead of specifically to a particular
> proportion scheduler policy.
> The correct solution is for the app to use a directed yield and a policy
> that can directly support it so that OpenGL can guaratee a frame rate
> governed by CPU bandwidth allocated by the scheduler.
> Will is working on such a mechanism now.

What? AFAIK the CFS patches already implement directed yields.

-- wli