linux-kernel - Re: 2.6.33 & 2.6.34-rc6: Huge number of Load Balancing tick wakeups.

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Date:	Sun, 09 May 2010 09:28:50 +1000
From:	Nigel Cunningham <ncunningham@...a.org.au>
To:	Len Brown <lenb@...nel.org>
CC:	LKML <linux-kernel@...r.kernel.org>,
	Linux Power Management List <linux-pm@...ts.osdl.org>
Subject: Re: 2.6.33 & 2.6.34-rc6: Huge number of Load Balancing tick wakeups.

Hi Len.

On 09/05/10 05:16, Len Brown wrote:
> (linux-pm cc'd)
>
>> I'm seeing a huge number of load balancing tick wakeups, with both 2.6.33 and
>> current git (f1c448e0a9e99c76f4ece368714fb35a40a8daba).
>>
>> This has been reported as a bug in some distros:
>>
>> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=521944
>> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/524281
>
> Unclear if your sighting is the same as those two.
>
> What do you see if vmware is not present?

I still see a huge number, just not as huge. The number of load 
balancing ticks seems to increase with the number of ticks from other 
sources. Without vmware running I got:

Cn	          Avg residency
C0 (cpu running)        (14.5%)
polling		  0.2ms ( 0.0%)
C1 mwait	  0.0ms ( 0.0%)
C2 mwait	  0.1ms ( 1.7%)
C4 mwait	  1.1ms (83.8%)
P-states (frequencies)
Turbo Mode     1.2%
   2.21 Ghz     0.0%
   1.60 Ghz     0.0%
   1200 Mhz     0.1%
    800 Mhz    98.7%
Wakeups-from-idle per second : 907.4	interval: 15.0s
no ACPI power usage estimate available
Top causes for wakeups:
   42.1% (435.6)   [kernel scheduler] Load balancing tick
   21.2% (219.6)   [extra timer interrupt]
   10.2% (105.6)   plugin-containe
    9.5% ( 98.1)   pulseaudio
    1.7% ( 17.9)   [Rescheduling interrupts] <kernel IPI>
    1.7% ( 17.1)   [iwl3945] <interrupt>
    1.4% ( 14.8)   [kernel core] hrtimer_start (tick_sched_timer)
    1.4% ( 14.3)   [ata_piix] <interrupt>

> What do you see if you boot single user mode,
> how about with maxcpusx=1?

I'll try those later today and get back to you with more info.

Regards,

Nigel

> cheers,
> Len Brown, Intel Open Source Technology Center
>
>> PowerTOP 1.12   (C) 2007, 2008 Intel Corporation
>>
>> Collecting data for 15 seconds
>>
>>
>> Your CPU supports the following C-states : C1 C2 C3 C4
>> Your BIOS reports the following C-states : C1 C2 C4
>> Cn                Avg residency
>> C0 (cpu running)        (40.8%)
>> polling           0.7ms ( 0.1%)
>> C1 mwait          0.0ms ( 0.0%)
>> C2 mwait          0.1ms ( 3.2%)
>> C4 mwait          0.4ms (56.0%)
>> P-states (frequencies)
>> Turbo Mode     7.3%
>>    2.21 Ghz     0.7%
>>    1.60 Ghz     0.8%
>>    1200 Mhz     0.9%
>>     800 Mhz    90.3%
>> Wakeups-from-idle per second : 1727.3   interval: 15.0s
>> no ACPI power usage estimate available
>> Top causes for wakeups:
>>    53.0% (1983.1)   [kernel scheduler] Load balancing tick
>>    27.7% (1035.1)   vmware-vmx
>>     8.8% (330.6)   [extra timer interrupt]
>>     2.3% ( 85.5)   [TLB shootdowns]<kernel IPI>
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