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[nptl] Re: http://bugme.osdl.org/show_bug.cgi?id=3770
- To: Nick Piggin <piggin@cyberone.com.au>
- Subject: [nptl] Re: http://bugme.osdl.org/show_bug.cgi?id=3770
- From: Sebastien Decugis <sebastien.decugis@ext.bull.net>
- Date: Thu, 09 Dec 2004 12:05:14 +0100
- Cc: nptl@bullopensource.org
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- Delivered-To: bullopensource.org-nptl@bullopensource.org
- In-Reply-To: <41B82435.7020802@cyberone.com.au>
- Organization: Bull S.A.
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- Reply-to: nptl@bullopensource.org
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> >> Hi again, Nick
> >>
> >> I got the static version to work when I linked it to a vanilla glibc,
> >> not the one from Fedora...
> >>
> >> I've attached it to this mail.
> >>
> >> With this release I still get the same issue:
> >>
> >>
> >
> > OK, I can reproduce it here! Thanks.
> >
> > Give me a few days to work on it and I'll get back to you if I come up
> > with anything.
> >
>
> Ah, the problem is that when the driver thread has a higher priority
> than the
> worker threads, so when the driver goes into an infinite loop waiting, the
> workers which are on the same CPU don't get to schedule at all. Those
> that are
> on the other CPU are able to schedule, however.
>
> The driver really needs to sleep, use a mutex, use a lower priority, or
> something in order for it to work.
>
Well, actually, I think the kernel has to migrate those lower priority
threads on the 'free' CPU, as the SCHED_RR scheduling policy is clear on
this point: the same-priority threads are scheduled equally on the free
resource...
This was why this testcase was written at first; an it looks like the
kernel does not obey this rule.
What is your opinion?
Thanks,
Seb.
--
-------------------------------
Sebastien DECUGIS
NPTL Test & Trace Project
http://nptl.bullopensource.org/
"You may fail if you try.
You -will- fail if you don't."
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