From c19dfb267c28032293515a635eaefbf9194629ac Mon Sep 17 00:00:00 2001 From: Ulf Hansson Date: Tue, 25 Nov 2025 12:26:47 +0100 Subject: Documentation: power/cpuidle: Document the CPU system wakeup latency QoS Let's document how the new CPU system wakeup latency QoS limit can be used from user space, along with how the constraint is taken into account for s2idle and cpuidle. Reviewed-by: Dhruva Gole Reviewed-by: Kevin Hilman (TI) Tested-by: Kevin Hilman (TI) Signed-off-by: Ulf Hansson Link: https://patch.msgid.link/20251125112650.329269-7-ulf.hansson@linaro.org Signed-off-by: Rafael J. Wysocki --- Documentation/admin-guide/pm/cpuidle.rst | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'Documentation/admin-guide') diff --git a/Documentation/admin-guide/pm/cpuidle.rst b/Documentation/admin-guide/pm/cpuidle.rst index 0c090b076224..be4c1120e3f0 100644 --- a/Documentation/admin-guide/pm/cpuidle.rst +++ b/Documentation/admin-guide/pm/cpuidle.rst @@ -580,6 +580,15 @@ the given CPU as the upper limit for the exit latency of the idle states that they are allowed to select for that CPU. They should never select any idle states with exit latency beyond that limit. +While the above CPU QoS constraints apply to CPU idle time management, user +space may also request a CPU system wakeup latency QoS limit, via the +`cpu_wakeup_latency` file. This QoS constraint is respected when selecting a +suitable idle state for the CPUs, while entering the system-wide suspend-to-idle +sleep state, but also to the regular CPU idle time management. + +Note that, the management of the `cpu_wakeup_latency` file works according to +the 'cpu_dma_latency' file from user space point of view. Moreover, the unit +is also microseconds. Idle States Control Via Kernel Command Line =========================================== -- cgit v1.2.3