Re: Too many poll_idle cpu calls in kernel 3.2 rc-series
From: Srivatsa S. Bhat
Date: Mon Nov 28 2011 - 15:02:05 EST
Adding linux-pm mailing list to CC.
Thanks,
Srivatsa S. Bhat
On 11/28/2011 01:43 AM, Nicolas Kalkhof wrote:
> the kernel v3.2 series shows excessive poll_idle calls during system idle phases causing the cpu
> (mobile i7 2620M) to heat up and draw additional 10% more power. All kernel versions between
> 3.2-rc1 and 3.2-rc3 are affected. Perf Top and Powertop both show the same issue.
> I've posted a similar bug report before: http://marc.info/?l=linux-kernel&m=132164909313594&w=2
> and used perf top -U to verify the poll_idle calls as requested.
>
> dmesg and kernel .config attached.
>
> Could someone please confirm this issue?
>
> Thanks and Regards
> Nic
>
> perf top -U shows:
> Events: 30K cycles
> 97.88% [kernel] [k] poll_idle
> 0.17% [kernel] [k] sdhci_irq
> 0.08% [kernel] [k] unix_poll
> 0.06% [kernel] [k] _raw_spin_lock_irqsave
> 0.06% [kernel] [k] page_fault
> 0.05% [kernel] [k] fget_light
> 0.05% [kernel] [k] format_decode
> 0.04% [kernel] [k] kmem_cache_alloc
> 0.04% [kernel] [k] clear_page
> 0.04% [kernel] [k] _raw_spin_unlock_irqrestore
> 0.03% [kernel] [k] do_select
> 0.03% [kernel] [k] seq_printf
> 0.03% [kernel] [k] vfs_read
> 0.03% [kernel] [k] _raw_spin_lock
> 0.03% [kernel] [k] vsnprintf
> 0.03% [kernel] [k] number.clone.1
> 0.03% [kernel] [k] fput
>
> Powertop shows:
> n Avg residency P-states (frequencies)
> C0 (cpu running) ( 5.4%) Turbo Mode 1.5%
> polling 1.8ms (94.6%) 2.71 Ghz 0.1%
> C1 mwait 0.0ms ( 0.0%) 2.21 Ghz 0.1%
> C2 mwait 0.0ms ( 0.0%) 1400 Mhz 0.1%
> C3 mwait 0.0ms ( 0.0%) 800 Mhz 98.2%
> C4 mwait 0.0ms ( 0.0%)
> Wakeups-from-idle per second : 529.4 interval: 5.0s
>
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