Re: periods and deadlines in SCHED_DEADLINE

From: Gregory Haskins
Date: Tue Aug 03 2010 - 08:02:41 EST

Hello Peter, Steven, Thomas, et al. !

Its been a while.

>>> On 8/3/2010 at 04:16 AM, in message <1280823360.1923.419.camel@laptop>, Peter
Zijlstra <peterz@xxxxxxxxxxxxx> wrote:


> So we replace the global lock with cmpxchg like loops using 2 per-cpu
> locks. Our current SCHED_FIFO balancer does just this and is found to be
> a very good approximation of global-fifo (iirc there's one funny case,
> but I can't remember, maybe Steve or Gregory can remember the details).

The only thing I remember at the moment is that Steven and I found one last remaining bug in an extreme corner
case where priority order may be violated. Sadly, I can no longer recall the exact specifics and would have to dig
into the code to remember. The good news is I believe the issue is fixable. Its just a matter of impl+test, which
neither of us ever seem to have found the time to properly dedicate. Perhaps this will be the catalyst ;)


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