Re: soft lockup - CPU#1 stuck for 15s! [swapper:0]

From: Arjan van de Ven
Date: Sun Dec 09 2007 - 17:32:19 EST


On Sun, 9 Dec 2007 16:57:38 -0500
"Parag Warudkar" <parag.warudkar@xxxxxxxxx> wrote:

> On Dec 8, 2007 6:12 PM, Parag Warudkar <parag.warudkar@xxxxxxxxx>
> wrote:
> > No problems after disabling CONFIG_HIGHRES_TIMERS , CONFIG_CPU_IDLE
> > and CONFIG_NO_HZ.
> >
> > I will try enabling them one by one - HRT, NOHZ and CPU_IDLE last -
> > that way we can at least tell what is required to be hit with this
> > problem.
>
> Looks like CPU_IDLE=y is necessary for the problem to show up.
> With CPU_IDLE=n HRT+NO_HZ+TICK_ONESHOT does not give soft lockup
> problems. (Actually with HIGH_RES_TIMERS=NO_HZ=TICK_ONESHOT=y I do
> see short freezes on ssh - when I cannot type anything for may be a
> second even under 100% idle. But Soft Lock up doesnt show up in dmesg
> with this configuration.)


starts to sound like something is turning off the clock during a somewhat deeper C-state...
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