Re: [PATCH v1 1/2] cpuidle: governors: teo: Fix tick_intercepts handling in teo_update()

From: Christian Loehle
Date: Mon Nov 17 2025 - 04:13:17 EST


On 11/16/25 12:34, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> The condition deciding whether or not to increase cpu_data->tick_intercepts
> in teo_update() is reverse, so fix it.
>
> Fixes: d619b5cc6780 ("cpuidle: teo: Simplify counting events used for tick management")
> Cc: All applicable <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
>
> I'm planning to apply this for 6.19 on top of
>
> https://lore.kernel.org/linux-pm/6228387.lOV4Wx5bFT@rafael.j.wysocki/
>
> because that patch (indirectly) depends on commit d619b5cc6780.
>
> ---
> drivers/cpuidle/governors/teo.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/drivers/cpuidle/governors/teo.c
> +++ b/drivers/cpuidle/governors/teo.c
> @@ -251,7 +251,7 @@ static void teo_update(struct cpuidle_dr
> cpu_data->state_bins[idx_timer].hits += PULSE;
> } else {
> cpu_data->state_bins[idx_duration].intercepts += PULSE;
> - if (TICK_NSEC <= measured_ns)
> + if (measured_ns <= TICK_NSEC)

nit: Why <= instead of <?
I guess it really doesn't matter with measured_ns only being a rough approximation
with an error in the order of wakeup-latency.

Reviewed-by:
Christian Loehle <christian.loehle@xxxxxxx>

Let me go write some tests for all these edge cases :/

IIRC Aboorva's power systems have no idle state deeper than TICK_NSEC, so
this might make a big difference here, hence CCed.