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4b603f1551
Currently, rq->idle_stamp is only used to calculate avg_idle during wakeups. This means other paths that move a task to an idle CPU such as fork/clone, execve, or migrations, do not end the CPU's idle status in the scheduler's eyes, leading to an inaccurate avg_idle. This patch introduces update_rq_avg_idle() to provide a more accurate measurement of CPU idle duration. By invoking this helper in put_prev_task_idle(), we ensure avg_idle is updated whenever a CPU stops being idle, regardless of how the new task arrived. Testing on an 80-core Ampere Altra (ARMv8) with 6.19-rc5 baseline: - Hackbench : +7.2% performance gain at 16 threads. - Schbench: Reduced p99.9 tail latencies at high concurrency. Signed-off-by: Shubhang Kaushik <shubhang@os.amperecomputing.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org> Tested-by: Shubhang Kaushik <shubhang@os.amperecomputing.com> Link: https://patch.msgid.link/20260121-v8-patch-series-v8-1-b7f1cbee5055@os.amperecomputing.com