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SubjectRe: cpuidle:powernv: Make the snooze timeout dynamic.
Date
On Thu, 2018-05-31 at 12:15:09 UTC, "Gautham R. Shenoy" wrote:
> From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
>
> The commit 78eaa10f027c ("cpuidle: powernv/pseries: Auto-promotion of
> snooze to deeper idle state") introduced a timeout for the snooze idle
> state so that it could be eventually be promoted to a deeper idle
> state. The snooze timeout value is static and set to the target
> residency of the next idle state, which would train the cpuidle
> governor to pick the next idle state eventually.
>
> The unfortunate side-effect of this is that if the next idle state(s)
> is disabled, the CPU will forever remain in snooze, despite the fact
> that the system is completely idle, and other deeper idle states are
> available.
>
> This patch fixes the issue by dynamically setting the snooze timeout
> to the target residency of the next enabled state on the device.
>
> Before Patch
> Reviewed-by: Balbir Singh <bsingharora@gmail.com>
>
> ==================
> POWER8 : Only nap disabled.
> $cpupower monitor sleep 30
> sleep took 30.01297 seconds and exited with status 0
> |Idle_Stats
> PKG |CORE|CPU | snoo | Nap | Fast
> 0| 8| 0| 96.41| 0.00| 0.00
> 0| 8| 1| 96.43| 0.00| 0.00
> 0| 8| 2| 96.47| 0.00| 0.00
> 0| 8| 3| 96.35| 0.00| 0.00
> 0| 8| 4| 96.37| 0.00| 0.00
> 0| 8| 5| 96.37| 0.00| 0.00
> 0| 8| 6| 96.47| 0.00| 0.00
> 0| 8| 7| 96.47| 0.00| 0.00
>
> POWER9: Shallow states (stop0lite, stop1lite, stop2lite, stop0, stop1,
> stop2) disabled:
> $cpupower monitor sleep 30
> sleep took 30.05033 seconds and exited with status 0
> |Idle_Stats
> PKG |CORE|CPU | snoo | stop | stop | stop | stop | stop | stop | stop | stop
> 0| 16| 0| 89.79| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00
> 0| 16| 1| 90.12| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00
> 0| 16| 2| 90.21| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00
> 0| 16| 3| 90.29| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00
>
> After Patch
> ======================
> POWER8 : Only nap disabled.
> $ cpupower monitor sleep 30
> sleep took 30.01200 seconds and exited with status 0
> |Idle_Stats
> PKG |CORE|CPU | snoo | Nap | Fast
> 0| 8| 0| 16.58| 0.00| 77.21
> 0| 8| 1| 18.42| 0.00| 75.38
> 0| 8| 2| 4.70| 0.00| 94.09
> 0| 8| 3| 17.06| 0.00| 81.73
> 0| 8| 4| 3.06| 0.00| 95.73
> 0| 8| 5| 7.00| 0.00| 96.80
> 0| 8| 6| 1.00| 0.00| 98.79
> 0| 8| 7| 5.62| 0.00| 94.17
>
> POWER9: Shallow states (stop0lite, stop1lite, stop2lite, stop0, stop1,
> stop2) disabled:
>
> $cpupower monitor sleep 30
> sleep took 30.02110 seconds and exited with status 0
> |Idle_Stats
> PKG |CORE|CPU | snoo | stop | stop | stop | stop | stop | stop | stop | stop
> 0| 0| 0| 0.69| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 9.39| 89.70
> 0| 0| 1| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 0.05| 93.21
> 0| 0| 2| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 89.93
> 0| 0| 3| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 0.00| 93.26
>
> Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/0a4ec6aa035a52c422eceb2ed51ed8

cheers

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