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SubjectRe: 2.6.33 & 2.6.34-rc6: Huge number of Load Balancing tick wakeups.
Hi again.

On 09/05/10 05:16, Len Brown wrote:
> What do you see if vmware is not present?
> What do you see if you boot single user mode,
> how about with maxcpusx=1?

Repeated the tests, just booting into X (xfce) - except for the init S
test. No programs were started and wifi was turned off.

1) No vmware (etc)

Cn Avg residency
C0 (cpu running) ( 3.7%)
polling 0.0ms ( 0.0%)
C1 mwait 0.0ms ( 0.0%)
C2 mwait 0.1ms ( 0.3%)
C4 mwait 5.4ms (96.0%)
P-states (frequencies)
Turbo Mode 1.4%
2.21 Ghz 0.0%
1.60 Ghz 0.0%
1200 Mhz 0.0%
800 Mhz 98.6%
Wakeups-from-idle per second : 202.7 interval: 15.0s
no ACPI power usage estimate available
Top causes for wakeups:
56.1% (128.5) [kernel scheduler] Load balancing tick
13.1% ( 30.1) [extra timer interrupt]
6.9% ( 15.9) [ata_piix] <interrupt>

2) Above + maxcpus=1

Cn Avg residency
C0 (cpu running) ( 4.0%)
polling 0.0ms ( 0.0%)
C1 mwait 0.0ms ( 0.0%)
C2 mwait 0.4ms ( 0.2%)
C4 mwait 16.0ms (95.9%)
P-states (frequencies)
Turbo Mode 6.0%
2.21 Ghz 0.0%
1.60 Ghz 0.0%
1200 Mhz 0.0%
800 Mhz 94.0%
Wakeups-from-idle per second : 64.5 interval: 15.0s
no ACPI power usage estimate available
Top causes for wakeups:
39.6% ( 46.3) [kernel scheduler] Load balancing tick
12.3% ( 14.3) [ata_piix] <interrupt>

(No idea why you need a load balancing tick with one core!)

3) Init S, without maxcpus=1

Cn Avg residency
C0 (cpu running) ( 0.0%)
polling 0.0ms ( 0.0%)
C1 mwait 0.0ms ( 0.0%)
C2 mwait 0.1ms ( 0.0%)
C4 mwait 48.9ms (100.0%)
P-states (frequencies)
Turbo Mode 0.0%
2.21 Ghz 0.0%
1.60 Ghz 0.0%
1200 Mhz 0.0%
800 Mhz 100.0%
Wakeups-from-idle per second : 21.4 interval: 15.0s
no ACPI power usage estimate available
Top causes for wakeups:
33.5% ( 10.3) [kernel core] hrtimer_start (tick_sched_timer)
16.1% ( 4.9) [kernel core] cursor_timer_handler (cursor_timer_handler)
15.9% ( 4.9) [kernel scheduler] Load balancing tick
12.8% ( 3.9) [kernel core] usb_hcd_poll_rh_status (rh_timer_func)
9.3% ( 2.9) [ahci] <interrupt>

I also tried the patch Dominik provided, and it didn't seem to make a
difference:
P-states (frequencies)
Turbo Mode 3.7%
2.21 Ghz 0.0%
1.60 Ghz 0.0%
1200 Mhz 0.6%
800 Mhz 95.7%
Wakeups-from-idle per second : 236.7 interval: 15.0s
no ACPI power usage estimate available
Top causes for wakeups:
55.4% (119.7) [kernel scheduler] Load balancing tick
9.7% ( 20.9) skype
7.7% ( 16.5) [ata_piix] <interrupt>

Regards,

Nigel


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