On Mon, 28 Jun 2004 17:08:05 +0200, Xavier Leroy <xavier.leroy@inria.fr> wrote:
> 
> The 2.6 Linux kernels changed the behavior of sched_yield() in a way
> that causes the unfairness you observed.  Other threaded applications
> are affected, including Open Office (!).  My belief is that it's
> really a bug in 2.6 kernels and that the new behavior of sched_yield(),
> while technically conformant to the POSIX specs, lowers the quality of
> implementation quite a lot.
> 
> (I seem to remember from my LinuxThreads development days that this
> isn't the first time the kernel developers broke sched_yield(), then
> realized their error.)

I know this comes a bit late in this 'thread', but there's been
discussion on Slashdot on a new scheduler framework called Bossa. I
posted a quote from Xavier's discussion of sched_yield, and another
poster replied. In brief:

"...OpenOffice.org and Ocaml have to wait too long for their next CPU
quantum, but that's because they are CPU bound tasks and it's their
own fault.

"The bug was in past versions of Linux where, although it was
pre-emptive, sched_yield was allowed some power - it should have been
ignored in user-space and the scheduler decided what gets CPU and
when. Depending on that bug is also a bug and the mis-users deserve
everything they get."

The full reply can be read at:

  <http://slashdot.org/comments.pl?sid=113880&cid=9655540>

-- 
 Don Wakefield
don.wakefield@gmail.com

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