From: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
To: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Ankita Garg <ankita@in.ibm.com>,
linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org,
linux-pm@lists.linux-foundation.org, thomas.abraham@linaro.org,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Matthew Garrett <mjg59@srcf.ucam.org>,
Arjan van de Ven <arjan@infradead.org>
Subject: Re: [PATCH 00/10] mm: Linux VM Infrastructure to support Memory Power Management
Date: Wed, 29 Jun 2011 23:47:55 +0530 [thread overview]
Message-ID: <20110629181755.GG3646@dirshya.in.ibm.com> (raw)
In-Reply-To: <1309370342.11430.604.camel@nimitz>
* Dave Hansen <dave@linux.vnet.ibm.com> [2011-06-29 10:59:02]:
> On Wed, 2011-06-29 at 23:12 +0530, Ankita Garg wrote:
> > 4. The kernel must have a mechanism to maintain utilization
> > statistics pertaining to a piece of hardware, so that it can
> > trigger the hardware to power it off
>
> Having statistics like this would certainly be nice, but how important
> _is_ it? Is it really a show-stopper? There's some stuff today, like
> the NPT/EPT support in KVM where we don't even have visibility in to
> when a given page is referenced.
>
> It's also going to be a pain to track kernel references. On x86, our
> kernel linear mapping uses 1GB pages when it can, and those are greater
> than the 512MB granularity that we've been talking about here. It's
> even larger on powerpc. I'm also pretty sure we don't even _look_ at
> the referenced bits in the kernel page tables. We'll definitely need
> some infrastructure to do that.
Utilization is all about allocated vs free and at most 'type of
allocation'. We are not looking at actual reference rates from page
tables. A free or unallocated page is not going to be referenced.
> > 5. Being able to group these pieces of hardware for purpose of
> > higher savings.
>
> Do you really mean group, or do you mean "turn as many off as possible"?
Grouping based on hardware topology could help save more power at
higher granularity. In most cases just turning as many off as
possible will work. But the design should allow grouping based on
certain rules or hierarchies.
--Vaidy
next prev parent reply other threads:[~2011-06-29 18:18 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-27 12:31 [PATCH 00/10] mm: Linux VM Infrastructure to support Memory Power Management Ankita Garg
2011-05-27 12:31 ` [PATCH 01/10] mm: Introduce the memory regions data structure Ankita Garg
2011-05-27 15:30 ` Dave Hansen
2011-05-27 18:20 ` Vaidyanathan Srinivasan
2011-05-27 21:31 ` Dave Hansen
2011-05-29 8:16 ` Ankita Garg
2011-05-31 17:34 ` Dave Hansen
2011-06-02 8:54 ` Ankita Garg
2011-05-27 12:31 ` [PATCH 02/10] mm: Helper routines Ankita Garg
2011-05-27 12:31 ` [PATCH 03/10] mm: Init zones inside memory regions Ankita Garg
2011-05-27 12:31 ` [PATCH 04/10] mm: Refer to zones from " Ankita Garg
2011-05-27 12:31 ` [PATCH 05/10] mm: Create zonelists Ankita Garg
2011-05-27 12:31 ` [PATCH 06/10] mm: Verify zonelists Ankita Garg
2011-05-27 12:31 ` [PATCH 07/10] mm: Modify vmstat Ankita Garg
2011-05-27 12:31 ` [PATCH 08/10] mm: Modify vmscan Ankita Garg
2011-05-27 12:31 ` [PATCH 09/10] mm: Reflect memory region changes in zoneinfo Ankita Garg
2011-05-27 12:31 ` [PATCH 10/10] mm: Create memory regions at boot-up Ankita Garg
2011-05-28 14:39 ` Jean-Christophe PLAGNIOL-VILLARD
2011-05-28 7:56 ` [PATCH 00/10] mm: Linux VM Infrastructure to support Memory Power Management Andrew Morton
2011-05-28 13:16 ` Ankita Garg
2011-06-09 18:52 ` Paul E. McKenney
2011-06-10 0:51 ` Kyungmin Park
2011-06-10 15:11 ` Paul E. McKenney
2011-06-10 15:59 ` Matthew Garrett
2011-06-10 16:55 ` Paul E. McKenney
2011-06-10 17:05 ` Matthew Garrett
2011-06-10 17:19 ` Paul E. McKenney
2011-06-10 17:23 ` Matthew Garrett
2011-06-10 17:52 ` Paul E. McKenney
2011-06-10 18:08 ` Matthew Garrett
2011-06-10 18:47 ` Paul E. McKenney
2011-06-10 19:23 ` Matthew Garrett
2011-06-10 19:37 ` Paul E. McKenney
2011-06-10 20:12 ` Matthew Garrett
2011-06-11 3:02 ` Arjan van de Ven
2011-06-11 17:06 ` Paul E. McKenney
2011-06-11 17:26 ` Arjan van de Ven
2011-06-12 23:07 ` Paul E. McKenney
2011-06-13 14:28 ` Arjan van de Ven
2011-06-13 23:04 ` Paul E. McKenney
2011-06-14 8:51 ` Ankita Garg
2011-06-15 16:53 ` Ankita Garg
2011-06-18 4:08 ` Arjan van de Ven
2011-06-10 17:33 ` Ankita Garg
2011-06-11 17:08 ` Paul E. McKenney
2011-07-12 5:31 ` amit kachhap
2011-06-13 4:47 ` KAMEZAWA Hiroyuki
2011-06-16 4:20 ` Ankita Garg
2011-06-16 9:12 ` KAMEZAWA Hiroyuki
2011-06-17 15:28 ` Ankita Garg
2011-06-19 23:53 ` KAMEZAWA Hiroyuki
2011-06-16 16:04 ` Dave Hansen
2011-06-17 10:03 ` Ankita Garg
2011-06-29 13:00 ` Ankita Garg
2011-06-29 17:06 ` Dave Hansen
2011-06-29 17:42 ` Ankita Garg
2011-06-29 17:59 ` Dave Hansen
2011-06-29 18:17 ` Vaidyanathan Srinivasan [this message]
2011-06-30 4:37 ` Ankita Garg
2011-06-29 20:11 ` Andi Kleen
2011-06-30 5:11 ` Ankita Garg
2011-06-29 18:07 ` Vaidyanathan Srinivasan
2011-07-06 8:45 ` Pekka Enberg
2011-07-06 9:01 ` Pekka Enberg
2011-07-06 16:50 ` Vaidyanathan Srinivasan
2011-07-06 16:41 ` Vaidyanathan Srinivasan
2011-07-06 20:20 ` david
2011-07-07 4:54 ` Ankita Garg
2011-07-07 18:00 ` Pekka Enberg
2011-07-08 1:32 ` david
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