workqueue: Show the latest workqueue name in /proc/PID/{comm,stat,status}
There can be a lot of workqueue workers and they all show up with the
cryptic kworker/* names making it difficult to understand which is
doing what and how they came to be.
# ps -ef | grep kworker
root 4 2 0 Feb25 ? 00:00:00 [kworker/0:0H]
root 6 2 0 Feb25 ? 00:00:00 [kworker/u112:0]
root 19 2 0 Feb25 ? 00:00:00 [kworker/1:0H]
root 25 2 0 Feb25 ? 00:00:00 [kworker/2:0H]
root 31 2 0 Feb25 ? 00:00:00 [kworker/3:0H]
...
This patch makes workqueue workers report the latest workqueue it was
executing for through /proc/PID/{comm,stat,status}. The extra
information is appended to the kthread name with intervening '+' if
currently executing, otherwise '-'.
# cat /proc/25/comm
kworker/2:0-events_power_efficient
# cat /proc/25/stat
25 (kworker/2:0-events_power_efficient) I 2 0 0 0 -1 69238880 0 0...
# grep Name /proc/25/status
Name: kworker/2:0-events_power_efficient
Unfortunately, ps(1) truncates comm to 15 characters,
# ps 25
PID TTY STAT TIME COMMAND
25 ? I 0:00 [kworker/2:0-eve]
making it a lot less useful; however, this should be an easy fix from
ps(1) side.
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Craig Small <csmall@enc.com.au>
diff --git a/fs/proc/array.c b/fs/proc/array.c
index f29221e..bb1d361 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -99,10 +99,13 @@ void proc_task_name(struct seq_file *m, struct task_struct *p, bool escape)
{
char *buf;
size_t size;
- char tcomm[sizeof(p->comm)];
+ char tcomm[64];
int ret;
- get_task_comm(tcomm, p);
+ if (p->flags & PF_WQ_WORKER)
+ wq_worker_comm(tcomm, sizeof(tcomm), p);
+ else
+ __get_task_comm(tcomm, sizeof(tcomm), p);
size = seq_get_buf(m, &buf);
if (escape) {