Message-ID: <52CBD96B.4050103@linux.vnet.ibm.com>
Date: Tue, 07 Jan 2014 16:09:39 +0530
From: Preeti U Murthy <preeti@linux.vnet.ibm.com>
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To: Peter Zijlstra <peterz@infradead.org>
CC: Vincent Guittot <vincent.guittot@linaro.org>, linux-kernel@vger.kernel.org,
        mingo@kernel.org, pjt@google.com, Morten.Rasmussen@arm.com,
        cmetcalf@tilera.com, tony.luck@intel.com, alex.shi@linaro.org,
        linaro-kernel@lists.linaro.org, rjw@sisk.pl,
        paulmck@linux.vnet.ibm.com, corbet@lwn.net, tglx@linutronix.de,
        len.brown@intel.com, arjan@linux.intel.com, amit.kucheria@linaro.org,
        james.hogan@imgtec.com, schwidefsky@de.ibm.com,
        heiko.carstens@de.ibm.com, Dietmar.Eggemann@arm.com
Subject: Re: [RFC] sched: CPU topology try
References: <20131105222752.GD16117@laptop.programming.kicks-ass.net> <1387372431-2644-1-git-send-email-vincent.guittot@linaro.org> <52CBCB85.8050607@linux.vnet.ibm.com> <20140107095039.GA2480@laptop.programming.kicks-ass.net>
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On 01/07/2014 03:20 PM, Peter Zijlstra wrote:
> On Tue, Jan 07, 2014 at 03:10:21PM +0530, Preeti U Murthy wrote:
>> What if we want to add arch specific flags to the NUMA domain? Currently
>> with Peter's patch:https://lkml.org/lkml/2013/11/5/239 and this patch,
>> the arch can modify the sd flags of the topology levels till just before
>> the NUMA domain. In sd_init_numa(), the flags for the NUMA domain get
>> initialized. We need to perhaps call into arch here to probe for
>> additional flags?
> 
> What are you thinking of? I was hoping all NUMA details were captured in
> the distance table.
> 
> Its far easier to talk of specifics in this case.
> 
If the processor can be core gated, then there is very little power
savings that we could yield from consolidating all the load onto a
single node in a NUMA domain. 6 cores on one node or 3 cores each on two
nodes, the power is drawn by 6 cores in all. So I was thinking under
this circumstance we might want to set the SD_SHARE_POWERDOMAIN flag at
the NUMA domain and spread the load if it favours the workload.

Regards
Preeti U Murthy

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