From c530a3c716b963625e43aa915e0de6b4d1ce8ad9 Mon Sep 17 00:00:00 2001 From: Chengming Zhou Date: Fri, 26 Aug 2022 00:41:02 +0800 Subject: [PATCH] sched/psi: Fix periodic aggregation shut off We don't want to wake periodic aggregation work back up if the task change is the aggregation worker itself going to sleep, or we'll ping-pong forever. Previously, we would use psi_task_change() in psi_dequeue() when task going to sleep, so this check was put in psi_task_change(). But commit 4117cebf1a9f ("psi: Optimize task switch inside shared cgroups") defer task sleep handling to psi_task_switch(), won't go through psi_task_change() anymore. So this patch move this check to psi_task_switch(). Fixes: 4117cebf1a9f ("psi: Optimize task switch inside shared cgroups") Signed-off-by: Chengming Zhou Signed-off-by: Peter Zijlstra (Intel) Acked-by: Johannes Weiner Link: https://lore.kernel.org/r/20220825164111.29534-2-zhouchengming@bytedance.com --- kernel/sched/psi.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c index ecb4b4ff4ce0..39463dcc16bb 100644 --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -796,7 +796,6 @@ void psi_task_change(struct task_struct *task, int clear, int set) { int cpu = task_cpu(task); struct psi_group *group; - bool wake_clock = true; void *iter = NULL; u64 now; @@ -806,19 +805,9 @@ void psi_task_change(struct task_struct *task, int clear, int set) psi_flags_change(task, clear, set); now = cpu_clock(cpu); - /* - * Periodic aggregation shuts off if there is a period of no - * task changes, so we wake it back up if necessary. However, - * don't do this if the task change is the aggregation worker - * itself going to sleep, or we'll ping-pong forever. - */ - if (unlikely((clear & TSK_RUNNING) && - (task->flags & PF_WQ_WORKER) && - wq_worker_last_func(task) == psi_avgs_work)) - wake_clock = false; while ((group = iterate_groups(task, &iter))) - psi_group_change(group, cpu, clear, set, now, wake_clock); + psi_group_change(group, cpu, clear, set, now, true); } void psi_task_switch(struct task_struct *prev, struct task_struct *next, @@ -854,6 +843,7 @@ void psi_task_switch(struct task_struct *prev, struct task_struct *next, if (prev->pid) { int clear = TSK_ONCPU, set = 0; + bool wake_clock = true; /* * When we're going to sleep, psi_dequeue() lets us @@ -867,13 +857,23 @@ void psi_task_switch(struct task_struct *prev, struct task_struct *next, clear |= TSK_MEMSTALL_RUNNING; if (prev->in_iowait) set |= TSK_IOWAIT; + + /* + * Periodic aggregation shuts off if there is a period of no + * task changes, so we wake it back up if necessary. However, + * don't do this if the task change is the aggregation worker + * itself going to sleep, or we'll ping-pong forever. + */ + if (unlikely((prev->flags & PF_WQ_WORKER) && + wq_worker_last_func(prev) == psi_avgs_work)) + wake_clock = false; } psi_flags_change(prev, clear, set); iter = NULL; while ((group = iterate_groups(prev, &iter)) && group != common) - psi_group_change(group, cpu, clear, set, now, true); + psi_group_change(group, cpu, clear, set, now, wake_clock); /* * TSK_ONCPU is handled up to the common ancestor. If we're tasked @@ -882,7 +882,7 @@ void psi_task_switch(struct task_struct *prev, struct task_struct *next, if (sleep) { clear &= ~TSK_ONCPU; for (; group; group = iterate_groups(prev, &iter)) - psi_group_change(group, cpu, clear, set, now, true); + psi_group_change(group, cpu, clear, set, now, wake_clock); } } }