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    SubjectRe: Too many poll_idle cpu calls in kernel 3.2 rc-series

    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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