io_uring/sqpoll: Do not set PF_NO_SETAFFINITY on sqpoll threads

[PATCH] io_uring/sqpoll: Do not set PF_NO_SETAFFINITY on sqpoll threads

Posted by Michal Koutný 2 years, 11 months ago

Users may specify a CPU where the sqpoll thread would run. This may
conflict with cpuset operations because of strict PF_NO_SETAFFINITY
requirement. That flag is unnecessary for polling "kernel" threads, see
the reasoning in commit 01e68ce08a30 ("io_uring/io-wq: stop setting
PF_NO_SETAFFINITY on io-wq workers"). Drop the flag on poll threads too.

Fixes: 01e68ce08a30 ("io_uring/io-wq: stop setting PF_NO_SETAFFINITY on io-wq workers")
Link: https://lore.kernel.org/all/20230314162559.pnyxdllzgw7jozgx@blackpad/
Signed-off-by: Michal Koutný <mkoutny@suse.com>
---
 io_uring/sqpoll.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/io_uring/sqpoll.c b/io_uring/sqpoll.c
index 0119d3f1a556..9db4bc1f521a 100644
--- a/io_uring/sqpoll.c
+++ b/io_uring/sqpoll.c
@@ -233,7 +233,6 @@ static int io_sq_thread(void *data)
 		set_cpus_allowed_ptr(current, cpumask_of(sqd->sq_cpu));
 	else
 		set_cpus_allowed_ptr(current, cpu_online_mask);
-	current->flags |= PF_NO_SETAFFINITY;
 
 	mutex_lock(&sqd->lock);
 	while (1) {
-- 
2.39.2

Re: [PATCH] io_uring/sqpoll: Do not set PF_NO_SETAFFINITY on sqpoll threads

Posted by Jens Axboe 2 years, 11 months ago

On Tue, 14 Mar 2023 19:33:32 +0100, Michal Koutný wrote:
> Users may specify a CPU where the sqpoll thread would run. This may
> conflict with cpuset operations because of strict PF_NO_SETAFFINITY
> requirement. That flag is unnecessary for polling "kernel" threads, see
> the reasoning in commit 01e68ce08a30 ("io_uring/io-wq: stop setting
> PF_NO_SETAFFINITY on io-wq workers"). Drop the flag on poll threads too.
> 
> 
> [...]

Applied, thanks!

[1/1] io_uring/sqpoll: Do not set PF_NO_SETAFFINITY on sqpoll threads
      commit: a5fc1441af7719e93dc7a638a960befb694ade89

Best regards,
-- 
Jens Axboe