The following commit has been merged into the sched/psi branch of tip:
Commit-ID: c530a3c716b963625e43aa915e0de6b4d1ce8ad9
Gitweb: https://git.kernel.org/tip/c530a3c716b963625e43aa915e0de6b4d1ce8ad9
Author: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
AuthorDate: Fri, 26 Aug 2022 00:41:02 +08:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Fri, 09 Sep 2022 11:08:30 +02:00
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 <zhouchengming@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220825164111.29534-2-zhouchengming@xxxxxxxxxxxxx
---
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 ecb4b4f..39463dc 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);
}
}
}
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