Message-ID: <1337116407.27694.118.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: David Rientjes <rientjes@google.com>
Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>,
        "Srivatsa S. Bhat" <srivatsa.bhat@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: Tue, 15 May 2012 23:13:27 +0200
In-Reply-To: <alpine.DEB.2.00.1205151346570.1656@chino.kir.corp.google.com>
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	 <alpine.DEB.2.00.1205141735050.25235@chino.kir.corp.google.com>
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	 <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>
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On Tue, 2012-05-15 at 14:05 -0700, David Rientjes wrote:
> Not sure what you're disagreeing with, it only happens with 
> MPOL_F_STATIC_NODES or MPOL_F_RELATIVE_NODES and I've clearly defined the 
> behavior in the man page.  I personally never had a use-case for 
> MPOL_F_RELATIVE_NODES but Paul Jackson asked that it be added for SGI when 
> we added mempolicy mode flags. 

So what you're saying is that:

task t: set_mempolicy(,mask=2-3);

add t to cpuset A

A.mems = 0-1
A.mems = 0-n

At which point t will again have 2-3, right?

My objection is that you'll have to keep the 2-3 mask around some place
because t->mems_allowed will be wrecked by cpuset actions.

Also, what does it mean to silently return to 2-3 after you've broken
that promise by forcing it to 0-1 using cpusets?


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