linux-kernel - Re: high power consumption in recent kernels

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Message-ID: <20100708124627.GA7754@gamma.logic.tuwien.ac.at>
Date:	Thu, 8 Jul 2010 21:46:27 +0900
From:	Norbert Preining <preining@...ic.at>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Arjan van de Ven <arjan@...radead.org>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	akpm <akpm@...ux-foundation.org>, Mike Galbraith <efault@....de>
Subject: Re: high power consumption in recent kernels

On Do, 08 Jul 2010, Peter Zijlstra wrote:
> Right, so that is a buggy patch, see the original discussion:
>   http://lkml.org/lkml/2010/4/26/249

Well, to me it wasn't so clear that this was buggy *for*my*system*
(core2)

> That said, we did frob something with the whole nohz thing, does the
> below cure anything:

Looks promising, reverting the old patch, adding that one, building,
running, unplugging ppower, powertop runs now since some time,
it seems that we are back to better situation:
Cn                Avg residency       P-states (frequencies)
C0 (cpu running)        ( 1.5%)       Turbo Mode     0.0%
C0                0.0ms ( 0.0%)         2.54 Ghz     0.0%
C1 mwait          0.0ms ( 0.0%)         1.60 Ghz     0.0%
C2 mwait          0.3ms ( 0.9%)          800 Mhz   100.0%
C6 mwait          8.5ms (97.6%)

Wakeups-from-idle per second : 139.9    interval: 15.0s
Power usage (ACPI estimate): 10.0W (8.8 hours) (long term: 1.7W,/50.9h)

Top causes for wakeups:
  32.2% ( 46.1)   [kernel scheduler] Load balancing tick
  20.4% ( 29.1)   [iwlagn] <interrupt>
  12.6% ( 18.0)   [extra timer interrupt]
   6.5% (  9.3)   [ahci] <interrupt>
   3.7% (  5.3)   [kernel core] hrtimer_start (tick_sched_timer)
   3.5% (  5.0)   syndaemon
   3.4% (  4.8)   [acpi] <interrupt>
   2.3% (  3.3)   yarssr

Power is going down to below 10W with brightness dimmed.

Thanks.

Best wishes

Norbert
------------------------------------------------------------------------
Norbert Preining            preining@...ist.ac.jp, logic.at, debian.org}
JAIST, Japan                                 TeX Live & Debian Developer
DSA: 0x09C5B094   fp: 14DF 2E6C 0307 BE6D AD76  A9C0 D2BF 4AA3 09C5 B094
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