The deeper the idle state, the lower the power consumption, but the longer the resume time. Some service are delay sensitive and very except the low resume time, like interrupt packet receiving mode.
And the "/sys/devices/system/cpu/cpuX/power/pm_qos_resume_latency_us" sysfs interface is used to set and get the resume latency limit on the cpuX for userspace. Please see the description in kernel document[1]. Each cpuidle governor in Linux select which idle state to enter based on this CPU resume latency in their idle task. The per-CPU PM QoS API can be used to control this CPU's idle state selection and limit just enter the shallowest idle state to low the delay after sleep by setting strict resume latency (zero value). [1] https://www.kernel.org/doc/html/latest/admin-guide/abi-testing.html?highlight=pm_qos_resume_latency_us#abi-sys-devices-power-pm-qos-resume-latency-us Huisong Li (2): power: introduce PM QoS API on CPU wide examples/l3fwd-power: add PM QoS configuration doc/guides/prog_guide/power_man.rst | 22 +++++ doc/guides/rel_notes/release_24_07.rst | 4 + examples/l3fwd-power/main.c | 29 +++++++ lib/power/meson.build | 2 + lib/power/rte_power_qos.c | 116 +++++++++++++++++++++++++ lib/power/rte_power_qos.h | 70 +++++++++++++++ lib/power/version.map | 2 + 7 files changed, 245 insertions(+) create mode 100644 lib/power/rte_power_qos.c create mode 100644 lib/power/rte_power_qos.h -- 2.22.0
