On Thu, May 17, 2007 at 05:18:41PM -0700, Bill Huey wrote:
> On Sun, May 13, 2007 at 05:38:53PM +0200, Ingo Molnar wrote:
> > Even a simple 3D app like glxgears does a sys_sched_yield() for every
> > frame it generates (!) on certain 3D cards, which in essence punishes
> > any scheduler that implements sys_sched_yield() in a sane manner. This
> > interaction of CFS's yield implementation with this user-space bug could
> > be the main reason why some testers reported SD to be handling 3D games
> > better than CFS. (SD uses a yield implementation similar to the vanilla
> > scheduler.)
> >
> > 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'.
>
> 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.
Follow up:
http://techpubs.sgi.com/library/tpl/cgi-bin/getdoc.cgi/0650/bks/SGI_Developer/books/REACT_PG/sgi_html/ch04.html
bill
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
