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

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Date:	Mon, 10 Dec 2007 11:19:50 +0530 (IST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Parag Warudkar <parag.warudkar@...il.com>
cc:	Arjan van de Ven <arjan@...radead.org>,
	Ingo Molnar <mingo@...e.hu>,
	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: soft lockup - CPU#1 stuck for 15s! [swapper:0]

On Sun, 9 Dec 2007, Parag Warudkar wrote:

> On Dec 8, 2007 6:12 PM, Parag Warudkar <parag.warudkar@...il.com> 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.)

Can you please apply the patch below ? It prints out the internal
state of the clockevents/timer system when the softlockup is detected.

Thanks,

	tglx

diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index 11df812..82f1a05 100644
--- a/kernel/softlockup.c
+++ b/kernel/softlockup.c
@@ -118,6 +118,7 @@ void softlockup_tick(void)
 		show_regs(regs);
 	else
 		dump_stack();
+	sysrq_timer_list_show();
 	spin_unlock(&print_lock);
 }
 
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