From: Arjan van de Ven <arjan@infradead.org>
To: Salman Qazi <sqazi@google.com>
Cc: svaidy@linux.vnet.ibm.com, Peter Zijlstra <peterz@infradead.org>,
mingo@elte.hu, linux-kernel@vger.kernel.org,
akpm@linux-foundation.org, linux-pm@lists.linux-foundation.org,
csadler@google.com, ranjitm@google.com, kenchen@google.com,
dawnchen@google.com
Subject: Re: [PATCH 0/3] [idled]: Idle Cycle Injector for power capping
Date: Tue, 20 Apr 2010 22:08:55 -0700 [thread overview]
Message-ID: <20100420220855.4619256b@infradead.org> (raw)
In-Reply-To: <k2y4352991a1004201052lbef1fd73g714d527e872162fd@mail.gmail.com>
On Tue, 20 Apr 2010 10:52:58 -0700
Salman Qazi <sqazi@google.com> wrote:
> For improving power savings in the non-SMT case, as Arjan suggested, I
> will make the changes for heuristically aligning the injection on
> multiple cores. This will not be perfect, but then because it's a
> power optimization, it doesn't have to always work. I presume that
> this works best when done according to the CPU hierarchy? That is, it
> is more beneficial to idle an entire socket than the same number of
> cores on different sockets?
not really; at least not for Intel CPUs.
The problem is that due to the cache coherency, as long as one cpu in
the system is awake, the memory controllers etc cannot go into a sleep
mode...
I would not be surprised if AMD has the same behavior... or anyone else
with an integrated memory controller for that matter.
--
Arjan van de Ven Intel Open Source Technology Centre
For development, discussion and tips for power savings,
visit http://www.lesswatts.org
next prev parent reply other threads:[~2010-04-21 5:07 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-14 0:08 [PATCH 0/3] [idled]: Idle Cycle Injector for power capping Salman
2010-04-14 0:08 ` [PATCH 1/3] [kidled]: introduce kidled Salman
2010-04-14 9:49 ` Andi Kleen
2010-04-14 15:41 ` Salman Qazi
2010-04-15 7:46 ` Peter Zijlstra
2010-04-14 0:08 ` [PATCH 2/3] [kidled]: Add eager injection Salman
2010-04-14 0:08 ` [PATCH 3/3] [kidled]: Introduce power capping priority and LB awareness Salman
2010-04-15 7:51 ` [PATCH 0/3] [idled]: Idle Cycle Injector for power capping Peter Zijlstra
2010-04-17 17:08 ` tytso
2010-04-17 17:57 ` Arjan van de Ven
2010-04-17 19:51 ` Peter Zijlstra
2010-04-19 17:20 ` Salman Qazi
2010-04-19 19:01 ` Peter Zijlstra
2010-04-20 1:00 ` Arjan van de Ven
2010-04-20 5:00 ` Vaidyanathan Srinivasan
2010-04-20 4:50 ` Vaidyanathan Srinivasan
2010-04-20 17:52 ` Salman Qazi
2010-04-21 5:08 ` Arjan van de Ven [this message]
2010-04-22 1:32 ` Mike Chan
2010-04-22 8:21 ` Peter Zijlstra
2010-04-22 19:02 ` Vaidyanathan Srinivasan
2010-04-17 16:40 ` Arjan van de Ven
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