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Date: Sun, 1 Jul 2007 10:31:02 +0200 From: Ingo Molnar <mingo@...e.hu> To: Willy Tarreau <w@....eu> Cc: linux-kernel@...r.kernel.org, Linus Torvalds <torvalds@...ux-foundation.org>, Andrew Morton <akpm@...ux-foundation.org>, Mike Galbraith <efault@....de>, Arjan van de Ven <arjan@...radead.org>, Thomas Gleixner <tglx@...utronix.de>, Dmitry Adamushko <dmitry.adamushko@...il.com>, Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com> Subject: Re: [patch] CFS scheduler, -v18 * Willy Tarreau <w@....eu> wrote: > Ingo, > > I've accidentally discovered a problem with -v18. > > Some time ago, I wrote a small program to prevent my laptop from > entering low-power mode, and noticed that after upgrading my laptop's > kernel from 2.4.20.9+cfs-v6 to 2.4.20.14+cfs-v18, it completely > freezes if I run this program. > > The program is trivial, it just sets its prio to nice +20 and forks a > busy loop. I've added the ability to stop the loop after a > user-definable number of iterations, and I can confirm that it > unfreezes when the loop ends. I'm not even root when I run it. hm, i tried your test-app and it causes no problems here. (which is not a surprise - your app starts a nice +19 busy loop, which is one of the common tests i do here too.) To further debug this, could you try to create a 'high priority shell' on a text console (i.e. not under X) that is SCHED_FIFO prio 98? Something like: chrt -f -p 98 $$ should do the trick. And then run this script: http://people.redhat.com/mingo/cfs-scheduler/tools/cfs-debug-info.sh before the test, during the test and after the test, from the high-prio shell session. (the shell runs at SCHED_FIFO, so the expectation would be for that it will be able to run during the test too) Then please send me the resulting 3 debug files. Thanks, Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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