Path: csiph.com!eternal-september.org!feeder.eternal-september.org!aioe.org!bofh.it!news.nic.it!robomod
From: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Newsgroups: linux.kernel
Subject: Re: [lkp] [fs] df4c0e36f1: NMI watchdog: BUG: soft lockup - CPU#0  stuck for 22s! [swapper/0:1]
Date: Mon, 02 Nov 2015 20:40:02 +0100
Message-ID: <qqt7s-R4-17@gated-at.bofh.it>
References: <qqilI-2Ut-11@gated-at.bofh.it> <qqjUt-3G6-13@gated-at.bofh.it> <qqrfj-8a7-5@gated-at.bofh.it>
X-Original-To: Dave Hansen <dave.hansen@intel.com>
Dkim-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=Um+ntKn2LC0a1wDfA2f5z7TaXMzEhw0SZHSAoX7J2CM=; b=J+PqNJ02dMm+TY/Rib2+1i4nbd9ztPWosfuqSse69DNEwI7f/LavSQwOQlmIDPqG9c af0YqMe9dpFEk9/s0hVoGa0Z2cbk3KMYL2fPECkUirSz2KI+zDa5efAbsalyxGSIVAf2 Ei0ff7MyQPDNSmoEJwEBeWVqNVunrp2YU+hkJizrcXnM9ww60eKo06aS8lJM5EM0ZZvJ QbgCR++DDEPHRftU//TkR2E3UcvV8JKl8C2VM9OG12i61rvSZnLEQ8qxrTu8UKlmC39f agu+96FDbnLvTt2bdjThU5kozc5mK40H+33yD1vTEEXo6e203nYf9485r3FasJmVN2Y4 gGqg==
MIME-Version: 1.0
X-Received: by 10.28.19.65 with SMTP id 62mr14664037wmt.35.1446492841575; Mon, 02 Nov 2015 11:34:01 -0800 (PST)
Content-Type: text/plain; charset=UTF-8
Sender: robomod@news.nic.it
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Approved: robomod@news.nic.it
Lines: 33
Organization: linux.* mail to news gateway
X-Original-Cc: kernel test robot <ying.huang@linux.intel.com>, LKP <lkp@01.org>, LKML <linux-kernel@vger.kernel.org>, Andrew Morton <akpm@linux-foundation.org>, David Rientjes <rientjes@google.com>, Pekka Enberg <penberg@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>, Andi Kleen <andi@firstfloor.org>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Christoph Lameter <cl@linux.com>, Sasha Levin <sasha.levin@oracle.com>, Konstantin Khlebnikov <koct9i@gmail.com>, Yuri Gribov <tetra2005@gmail.com>, Andrey Konovalov <adech.fo@gmail.com>, Konstantin Serebryany <kcc@google.com>, Dmitry Vyukov <dvyukov@google.com>, Linus Torvalds <torvalds@linux-foundation.org>
X-Original-Date: Mon, 2 Nov 2015 22:34:01 +0300
X-Original-Message-ID: <CAPAsAGzpTM84NEESPt_jY0i-+W2SB37KtW1TXy93e8R2F7rEtw@mail.gmail.com>
X-Original-References: <87611kakr3.fsf@yhuang-dev.intel.com> <CAPAsAGwVYSgXm0Rgbtim-5iFxhWaakc1emXQALKwYLm36OoVsw@mail.gmail.com> <56379FDE.6010603@intel.com>
X-Original-Sender: linux-kernel-owner@vger.kernel.org
Xref: csiph.com linux.kernel:1260908

2015-11-02 20:39 GMT+03:00 Dave Hansen <dave.hansen@intel.com>:
> On 11/02/2015 01:32 AM, Andrey Ryabinin wrote:
>> And the major factor here is number 2.
>>
>> In your dmesg:
>> [   67.891156] rbtree testing -> 570841 cycles
>> [   88.609636] augmented rbtree testing
>> [  116.546697] NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s!
>> [swapper/0:1]
>>
>>
>> I've tried to reproduce this, and got this:
>> [    0.693574] rbtree testing -> 15513 cycles
>> 570841/15513 = 36x times faster.
>>
>> [    1.159450] augmented rbtree testing -> 23675 cycles
>> [    1.864996]
>> It took less than a second, meanwhile in your case it didn't finish in
>> 22 seconds.
>>
>> This makes me think that your host is overloaded and the problem is on
>> your side.
>
> It's probably just a matter of putting some cond_resched()s in the test
> code.

Yes, but is it worthwhile? It's very likely that lockup will just
trigger in another place.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/