[PATCH v2] workqueue: Do not set CPU_INTENSIVE worker flags with wq_cpu_intensive_thresh_us=0

[PATCH v2] workqueue: Do not set CPU_INTENSIVE worker flags with wq_cpu_intensive_thresh_us=0

[Zqiang]

If the system start with workqueue.cpu_intensive_thresh_us=0, for running
per-cpu worker, the CPU_INTENSIVE flag will be set unconditionally in
wq_worker_tick(), this commit therefore disable set CPU_INTENSIVE and
directly return when workqueue.cpu_intensive_thresh_us=0.

Signed-off-by: Zqiang <qiang.zhang1211@gmail.com>
---

[   17.359725] workqueue: process_srcu hogged CPU for >0us 4 times, consider switching to WQ_UNBOUND
[   19.752679] workqueue: gc_worker hogged CPU for >0us 4 times, consider switching to WQ_UNBOUND
[   19.796721] workqueue: gc_worker hogged CPU for >0us 8 times, consider switching to WQ_UNBOUND
[   21.992637] workqueue: wait_rcu_exp_gp hogged CPU for >0us 4 times, consider switching to WQ_UNBOUND
[   27.143632] workqueue: kfree_rcu_monitor hogged CPU for >0us 4 times, consider switching to WQ_UNBOUND
[   27.143647] workqueue: kfree_rcu_monitor hogged CPU for >0us 8 times, consider switching to WQ_UNBOUND
[   38.472708] workqueue: reg_todo hogged CPU for >0us 4 times, consider switching to WQ_UNBOUND

 kernel/workqueue.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index c4f4ca0bd2af..eaea5386859e 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1152,6 +1152,7 @@ void wq_worker_tick(struct task_struct *task)
 	 * We probably want to make this prettier in the future.
 	 */
 	if ((worker->flags & WORKER_NOT_RUNNING) || READ_ONCE(worker->sleeping) ||
+						!wq_cpu_intensive_thresh_us ||
 	    worker->task->se.sum_exec_runtime - worker->current_at <
 	    wq_cpu_intensive_thresh_us * NSEC_PER_USEC)
 		return;
-- 
2.17.1

Re: [PATCH v2] workqueue: Do not set CPU_INTENSIVE worker flags with wq_cpu_intensive_thresh_us=0

[Tejun Heo]

Hello,

I rewrote the patch description and separated it out into a separate if
statement for readability. Applied to wq/for-6.5.

Thanks.

From 18c8ae813156a6855f026de80fffb91e1a28ab3d Mon Sep 17 00:00:00 2001
From: Zqiang <qiang.zhang1211@gmail.com>
Date: Thu, 25 May 2023 12:00:38 +0800
Subject: [PATCH] workqueue: Disable per-cpu CPU hog detection when
 wq_cpu_intensive_thresh_us is 0

If workqueue.cpu_intensive_thresh_us is set to 0, the detection mechanism
for CPU-hogging per-cpu work item will keep triggering spuriously:

  workqueue: process_srcu hogged CPU for >0us 4 times, consider switching to WQ_UNBOUND
  workqueue: gc_worker hogged CPU for >0us 4 times, consider switching to WQ_UNBOUND
  workqueue: gc_worker hogged CPU for >0us 8 times, consider switching to WQ_UNBOUND
  workqueue: wait_rcu_exp_gp hogged CPU for >0us 4 times, consider switching to WQ_UNBOUND
  workqueue: kfree_rcu_monitor hogged CPU for >0us 4 times, consider switching to WQ_UNBOUND
  workqueue: kfree_rcu_monitor hogged CPU for >0us 8 times, consider switching to WQ_UNBOUND
  workqueue: reg_todo hogged CPU for >0us 4 times, consider switching to WQ_UNBOUND

This commit therefore disables the CPU-hog detection mechanism when
workqueue.cpu_intensive_thresh_us is set to 0.

tj: Patch description updated and the condition check on
    cpu_intensive_thresh_us separated into a separate if statement for
    readability.

Signed-off-by: Zqiang <qiang.zhang1211@gmail.com>

Can you please use your full name as in "FIRST_NAME LAST_NAME <EMAIL>" when
signing-off patches in the future?

Thanks.

--
tejun

Re: [PATCH v2] workqueue: Do not set CPU_INTENSIVE worker flags with wq_cpu_intensive_thresh_us=0

[Z qiang]

>
> Hello,
>
> I rewrote the patch description and separated it out into a separate if
> statement for readability. Applied to wq/for-6.5.
>
> Thanks.
>
> From 18c8ae813156a6855f026de80fffb91e1a28ab3d Mon Sep 17 00:00:00 2001
> From: Zqiang <qiang.zhang1211@gmail.com>
> Date: Thu, 25 May 2023 12:00:38 +0800
> Subject: [PATCH] workqueue: Disable per-cpu CPU hog detection when
>  wq_cpu_intensive_thresh_us is 0
>
> If workqueue.cpu_intensive_thresh_us is set to 0, the detection mechanism
> for CPU-hogging per-cpu work item will keep triggering spuriously:
>
>   workqueue: process_srcu hogged CPU for >0us 4 times, consider switching to WQ_UNBOUND
>   workqueue: gc_worker hogged CPU for >0us 4 times, consider switching to WQ_UNBOUND
>   workqueue: gc_worker hogged CPU for >0us 8 times, consider switching to WQ_UNBOUND
>   workqueue: wait_rcu_exp_gp hogged CPU for >0us 4 times, consider switching to WQ_UNBOUND
>   workqueue: kfree_rcu_monitor hogged CPU for >0us 4 times, consider switching to WQ_UNBOUND
>   workqueue: kfree_rcu_monitor hogged CPU for >0us 8 times, consider switching to WQ_UNBOUND
>   workqueue: reg_todo hogged CPU for >0us 4 times, consider switching to WQ_UNBOUND
>
> This commit therefore disables the CPU-hog detection mechanism when
> workqueue.cpu_intensive_thresh_us is set to 0.
>
> tj: Patch description updated and the condition check on
>     cpu_intensive_thresh_us separated into a separate if statement for
>     readability.
>
> Signed-off-by: Zqiang <qiang.zhang1211@gmail.com>
>
> Can you please use your full name as in "FIRST_NAME LAST_NAME <EMAIL>" when
> signing-off patches in the future?
>

Because there are many people with the same name as me, so I use the
abbreviation of the name to distinguish,
but in the future I will use the full name  :) .

Thanks
Zqiang

>
> Thanks.
>
> --
> tejun