From: Thomas Gleixner <tglx@linutronix.de>
To: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Paul McKenney <paul.mckenney@linaro.org>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, linux-next <linux-next@vger.kernel.org>
Subject: Re: [next-20120823] NOHZ: local_softirq_pending 200 on s/r
Date: Thu, 23 Aug 2012 12:46:37 +0200 (CEST) [thread overview]
Message-ID: <alpine.LFD.2.02.1208231245510.2856@ionos> (raw)
In-Reply-To: <CA+icZUW2aUP=vjBeoksFU=NAVFMJEiBQy6sNKZczzRPEP9kOfw@mail.gmail.com>
On Thu, 23 Aug 2012, Sedat Dilek wrote:
> Hi,
>
> this week I was seeing the below NOHZ messages in my logs especially
> when suspending and resuming.
>
> Currently, I am using linux-next (next-20120823) on Ubuntu/precise
> AMD64 with a Intel S(a)N(dy)B(ridge)-CPU.
>
> $ dmesg | grep -A1 -B1 -i nohz
> [ 720.331819] Disabling non-boot CPUs ...
> [ 720.332035] NOHZ: local_softirq_pending 200
> [ 720.434312] smpboot: CPU 1 is now offline
> [ 720.434825] NOHZ: local_softirq_pending 200
> [ 720.538237] smpboot: CPU 2 is now offline
> [ 720.538676] NOHZ: local_softirq_pending 200
> [ 720.642162] smpboot: CPU 3 is now offline
>
> If I manually disable the cpuX... First I did not see NOHZ messages
> but then there were some lines seen especially when cpuX went offline
> (here: cpu1)
>
> # echo 0 >/sys/devices/system/cpu/cpu1/online
>
> [ dmeg ]
> [ 2605.515771] smpboot: CPU 1 is now offline
>
> The same with cpu2 and cpu3.
>
> Jack Winter confirmed to see similiar NOHZ messages also on
> v3.4.9-rt17 kernel (CPU: Core2Duo when no suspend performed):
>
> [15223.171585] NOHZ: local_softirq_pending 08
That's a different issue. That's a pending networking softirq when we
go idle. Unrelated to the RCU / hotplug issue you are observing.
> So, the issue is seen on linux-next and -rt kernels.
>
> According to Thomas "softirq 0x200 is the RCU one" and he requested me
> to address the issue to Paul on #linux-rt.
>
> Regards,
> - Sedat -
>
next prev parent reply other threads:[~2012-08-23 10:46 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-23 10:04 [next-20120823] NOHZ: local_softirq_pending 200 on s/r Sedat Dilek
2012-08-23 10:46 ` Thomas Gleixner [this message]
2012-08-23 15:43 ` Paul E. McKenney
2012-08-23 16:06 ` Sedat Dilek
2012-08-23 17:14 ` Paul E. McKenney
2012-08-23 18:55 ` Sedat Dilek
2012-08-23 19:09 ` Paul E. McKenney
2012-08-24 7:26 ` Mike Galbraith
2012-08-24 14:52 ` Paul E. McKenney
2012-08-24 15:40 ` Thomas Gleixner
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