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sched/psi: Fix periodic aggregation shut off

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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 4117cebf1a ("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: 4117cebf1a ("psi: Optimize task switch inside shared cgroups")
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lore.kernel.org/r/20220825164111.29534-2-zhouchengming@bytedance.com
This commit is contained in:
Chengming Zhou 2022-08-26 00:41:02 +08:00 committed by Peter Zijlstra
parent 0fb7b6f9d3
commit c530a3c716
1 changed files with 14 additions and 14 deletions
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28
kernel/sched/psi.c
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@ -796,7 +796,6 @@ void psi_task_change(struct task_struct *task, int clear, int set)
{ {
int cpu = task_cpu(task); int cpu = task_cpu(task);
struct psi_group *group; struct psi_group *group;
bool wake_clock = true;
void *iter = NULL; void *iter = NULL;
u64 now; u64 now;
@ -806,19 +805,9 @@ void psi_task_change(struct task_struct *task, int clear, int set)
psi_flags_change(task, clear, set); psi_flags_change(task, clear, set);
now = cpu_clock(cpu); 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))) 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, 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) { if (prev->pid) {
int clear = TSK_ONCPU, set = 0; int clear = TSK_ONCPU, set = 0;
bool wake_clock = true;
/* /*
* When we're going to sleep, psi_dequeue() lets us * 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; clear |= TSK_MEMSTALL_RUNNING;
if (prev->in_iowait) if (prev->in_iowait)
set |= TSK_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); psi_flags_change(prev, clear, set);
iter = NULL; iter = NULL;
while ((group = iterate_groups(prev, &iter)) && group != common) 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 * 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) { if (sleep) {
clear &= ~TSK_ONCPU; clear &= ~TSK_ONCPU;
for (; group; group = iterate_groups(prev, &iter)) 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);
} }
} }
} }