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Date: Wed, 07 Mar 2012 01:47:21 +0400
From: Konstantin Khlebnikov <khlebnikov@openvz.org>
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To: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Ingo Molnar <mingo@elte.hu>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Subject: Re: [PATCH bisected regression] sched: rebuild sched domains at suspend/resume
References: <20120306204357.13169.90791.stgit@zurg> <1331067743.11248.333.camel@twins>
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Peter Zijlstra wrote:
> On Wed, 2012-03-07 at 00:45 +0400, Konstantin Khlebnikov wrote:
>> This is fix for suspend/resume regression introduced in commit 8f2f748b0656
>> ("CPU hotplug, cpusets, suspend: Don't touch cpusets during suspend/resume")
>> Without this patch suspend always hangs on my thinkpad x220 (2 x CPU * HT).
>>
>> cpuset_update_active_cpus() not only juggles with bits in cpusets,
>> it also calls sched-domains rebuilding after all.
>>
>> This patch restores sched-domain rebuilds, as it was before that commit.
>
> This changelog also completely fails to explain what the problem was and
> how this patch sorts it without re-introducing the problems 8f2f748b0656
> was supposed to fix.

That patch removes cpuset bits clearing on suspend/resume cycle. My patch doesn't clear them too.
I don't know why these domain rebuilds are required, so I just returned them back.

>
> I'd rather revert the 'fix' and think about this more (its been broken
> pretty much forever anyway) than tinker on top like this.

Ok, "rc" isn't the best time that.