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

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Date:	Thu, 30 Sep 2010 15:59:02 +0900
From:	Norbert Preining <preining@...ic.at>
To:	"Alex,Shi" <alex.shi@...el.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	"Chen, Tim C" <tim.c.chen@...el.com>,
	"arjan@...radead.org" <arjan@...radead.org>,
	"efault@....de" <efault@....de>,
	"Li, Shaohua" <shaohua.li@...el.com>, tglx <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Zhao, Yakui" <yakui.zhao@...el.com>
Subject: Re: high power consumption in recent kernels

> The following line is different, the new code remove the nohz_ratelimit
> from irq_exit(). That may resolve your system too many interrupts
> issue. 
> 
> +               arch_needs_cpu(cpu)|| (inidle && nohz_ratelimit(cpu))) {

That is a very nice one ..., first time I came down
with inactive laptop, lowest brightness, down to below 8W:
Cn                Avg residency       P-states (frequencies)
C0 (cpu running)        ( 1.1%)       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 ( 0.8%)          800 Mhz    99.9%
C6 mwait         16.7ms (98.2%)

Wakeups-from-idle per second : 81.3     interval: 15.0s
Power usage (ACPI estimate): 7.9W (11.0 hours)

Top causes for wakeups:
  23.8% ( 18.1)   kworker/0:0
  14.0% ( 10.7)   [ahci] <interrupt>
  13.4% ( 10.2)   [kernel scheduler] Load balancing tick
   6.6% (  5.0)   syndaemon
   5.5% (  4.2)   Xorg
   5.5% (  4.2)   [extra timer interrupt]
   4.6% (  3.5)   [acpi] <interrupt>

Very nice, with activity and bluetooth and internet over bluetooth
I am back at 10.3W, but that is also fine.

Anything else you need to know (kernel was latest git, -rc6 AFAIR).

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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