From: Catalin Marinas <catalin.marinas@arm.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>,
Morten Rasmussen <Morten.Rasmussen@arm.com>,
David Lang <david@lang.hm>,
"len.brown@intel.com" <len.brown@intel.com>,
"alex.shi@intel.com" <alex.shi@intel.com>,
"corbet@lwn.net" <corbet@lwn.net>,
"peterz@infradead.org" <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
"efault@gmx.de" <efault@gmx.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linaro-kernel@lists.linaro.org" <linaro-kernel@lists.linaro.org>,
"preeti@linux.vnet.ibm.com" <preeti@linux.vnet.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>,
"pjt@google.com" <pjt@google.com>, Ingo Molnar <mingo@kernel.org>
Subject: Re: power-efficient scheduling design
Date: Mon, 24 Jun 2013 11:07:32 +0100 [thread overview]
Message-ID: <20130624100732.GB14982@arm.com> (raw)
In-Reply-To: <1372030320.3944.114.camel@pasglop>
On Mon, Jun 24, 2013 at 12:32:00AM +0100, Benjamin Herrenschmidt wrote:
> On Fri, 2013-06-21 at 14:34 -0700, Arjan van de Ven wrote:
> > On 6/21/2013 2:23 PM, Catalin Marinas wrote:
> > >>
> > >> oops sorry I misread your mail (lack of early coffee I suppose)
> > >>
> > >> I can see your point of having a thing for "did we ask for all the performance
> > >> we could ask for" prior to doing a load balance (although, for power efficiency,
> > >> if you have two tasks that could run in parallel, it's usually better to
> > >> run them in parallel... so likely we should balance anyway)
> > >
> > > Not necessarily, especially if parallel running implies powering up a
> > > full cluster just for one CPU (it depends on the hardware but for
> > > example a cluster may not be able to go in deeper sleep states unless
> > > all the CPUs in that cluster are idle).
> >
> > I guess it depends on the system
>
> Sort-of. We have something similar with threads on ppc. IE, the core can
> only really stop if all threads are. From a Linux persepctive it's a
> matter of how we define the scope of that 'cluster' Catalin is talking
> about. I'm sure you do too.
>
> Then there is the package, which adds MC etc...
I think we can say cluster == package so that we use some common
terminology. On a big.little configuration (TC2), we have 3xA7 in one
package and 2xA15 in the other. So to efficiently stop an entire package
(cluster, multi-core etc.) we need to stop all the CPUs it has.
--
Catalin
next prev parent reply other threads:[~2013-06-24 10:10 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-30 13:47 [RFC] Comparison of power-efficient scheduling patch sets Morten Rasmussen
2013-05-31 1:17 ` Alex Shi
2013-05-31 8:23 ` Alex Shi
2013-05-31 10:52 ` power-efficient scheduling design Ingo Molnar
2013-06-03 14:59 ` Arjan van de Ven
2013-06-03 15:43 ` Ingo Molnar
2013-06-04 15:03 ` Morten Rasmussen
2013-06-07 6:26 ` Preeti U Murthy
2013-06-20 15:23 ` Ingo Molnar
2013-06-05 9:56 ` Amit Kucheria
2013-06-07 6:03 ` Preeti U Murthy
2013-06-07 14:51 ` Catalin Marinas
2013-06-07 18:08 ` Preeti U Murthy
2013-06-07 17:36 ` David Lang
2013-06-09 4:33 ` Preeti U Murthy
2013-06-08 11:28 ` Catalin Marinas
2013-06-08 14:02 ` Rafael J. Wysocki
2013-06-09 3:42 ` Preeti U Murthy
2013-06-09 22:53 ` Catalin Marinas
2013-06-10 16:25 ` Daniel Lezcano
2013-06-12 0:27 ` David Lang
2013-06-12 1:48 ` Arjan van de Ven
2013-06-12 9:48 ` Amit Kucheria
2013-06-12 16:22 ` David Lang
2013-06-12 10:20 ` Catalin Marinas
2013-06-12 15:24 ` Arjan van de Ven
2013-06-12 17:04 ` Catalin Marinas
2013-06-12 9:50 ` Daniel Lezcano
2013-06-12 16:30 ` David Lang
2013-06-11 0:50 ` Rafael J. Wysocki
2013-06-13 4:32 ` Preeti U Murthy
2013-06-09 4:23 ` Preeti U Murthy
2013-06-07 15:23 ` Arjan van de Ven
2013-06-14 16:05 ` Morten Rasmussen
2013-06-17 11:23 ` Catalin Marinas
2013-06-18 1:37 ` David Lang
2013-06-18 10:23 ` Morten Rasmussen
2013-06-18 17:39 ` David Lang
2013-06-19 12:39 ` Morten Rasmussen
2013-06-18 15:20 ` Arjan van de Ven
2013-06-18 17:47 ` David Lang
2013-06-18 19:36 ` Arjan van de Ven
2013-06-19 15:39 ` Arjan van de Ven
2013-06-19 17:00 ` Morten Rasmussen
2013-06-19 17:08 ` Arjan van de Ven
2013-06-21 8:50 ` Morten Rasmussen
2013-06-21 15:29 ` Arjan van de Ven
2013-06-21 15:38 ` Arjan van de Ven
2013-06-21 21:23 ` Catalin Marinas
2013-06-21 21:34 ` Arjan van de Ven
2013-06-23 23:32 ` Benjamin Herrenschmidt
2013-06-24 10:07 ` Catalin Marinas [this message]
2013-06-24 15:26 ` Arjan van de Ven
2013-06-24 21:59 ` Benjamin Herrenschmidt
2013-06-24 23:10 ` Arjan van de Ven
2013-06-18 19:06 ` Catalin Marinas
2013-06-21 15:06 ` Morten Rasmussen
2013-06-23 10:55 ` Ingo Molnar
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