Messages in this thread | | | From | Stewart Smith <> | Subject | Re: [PATCH] cpuidle:powernv: Make the snooze timeout dynamic. | Date | Tue, 05 Jun 2018 13:47:55 +1000 |
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Michael Ellerman <mpe@ellerman.id.au> writes: > "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> writes: > >> 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. > > That sounds like a bug, I'll add? > > Fixes: 78eaa10f027c ("cpuidle: powernv/pseries: Auto-promotion of snooze to deeper idle state") > Cc: stable@vger.kernel.org # v4.2+
Yes, it's a bug - we had a customer bug because we lacked this that meant we had to do firmware changes rather than just tweaking what stop states were used.
-- Stewart Smith OPAL Architect, IBM.
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