Message-ID: <1337203449.4281.15.camel@twins>
Subject: Re: [PATCH v3 5/5] cpusets, suspend: Save and restore cpusets
 during suspend/resume
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: David Rientjes <rientjes@google.com>,
        Nishanth Aravamudan <nacc@linux.vnet.ibm.com>, mingo@kernel.org,
        pjt@google.com, paul@paulmenage.org, akpm@linux-foundation.org,
        rjw@sisk.pl, nacc@us.ibm.com, paulmck@linux.vnet.ibm.com,
        tglx@linutronix.de, seto.hidetoshi@jp.fujitsu.com, tj@kernel.org,
        mschmidt@redhat.com, berrange@redhat.com, nikunj@linux.vnet.ibm.com,
        vatsa@linux.vnet.ibm.com, liuj97@gmail.com,
        linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Date: Wed, 16 May 2012 23:24:09 +0200
In-Reply-To: <4FB2D5CB.6090209@linux.vnet.ibm.com>
References: <20120513231325.3566.37740.stgit@srivatsabhat>
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	 <alpine.DEB.2.00.1205141735050.25235@chino.kir.corp.google.com>
	 <20120515014042.GA9774@linux.vnet.ibm.com>
	 <alpine.DEB.2.00.1205142055160.10906@chino.kir.corp.google.com>
	 <20120515044539.GA25256@linux.vnet.ibm.com>
	 <alpine.DEB.2.00.1205151106490.24304@chino.kir.corp.google.com>
	 <1337112653.27694.110.camel@twins>
	 <alpine.DEB.2.00.1205151346570.1656@chino.kir.corp.google.com>
	 <1337116107.27694.114.camel@twins>
	 <alpine.DEB.2.00.1205151414210.1656@chino.kir.corp.google.com>
	 <4FB2CDAD.4020306@linux.vnet.ibm.com>
	 <alpine.DEB.2.00.1205151444260.1656@chino.kir.corp.google.com>
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On Wed, 2012-05-16 at 03:46 +0530, Srivatsa S. Bhat wrote:
> 
> However, the cpu_active_mask was introduced to handle situations where hotplug
> transition is still in progress, and the scheduler needs to take appropriate
> decisions even with some of its data-structures in an inconsistent/stale state.
> But once the hotplug operation is completed, the scheduler doesn't need to
> depend on cpu_active_mask.

> (And on those lines, making the scheduler work correctly even in such cases
> is only a good-to-have as a robustness measure and not a "bugfix".) 

I think those 2(?) cases you found not covered by active mask could
actually happen during a hotplug. So far they simply haven't.
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