* [PATCH AUTOSEL 6.1 32/33] io_uring: unlock sqd->lock before sq thread release CPU
[not found] <[email protected]>
@ 2023-05-31 13:41 ` Sasha Levin
0 siblings, 0 replies; only message in thread
From: Sasha Levin @ 2023-05-31 13:41 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Wenwen Chen, Kanchan Joshi, Jens Axboe, Sasha Levin, io-uring
From: Wenwen Chen <[email protected]>
[ Upstream commit 533ab73f5b5c95dcb4152b52d5482abcc824c690 ]
The sq thread actively releases CPU resources by calling the
cond_resched() and schedule() interfaces when it is idle. Therefore,
more resources are available for other threads to run.
There exists a problem in sq thread: it does not unlock sqd->lock before
releasing CPU resources every time. This makes other threads pending on
sqd->lock for a long time. For example, the following interfaces all
require sqd->lock: io_sq_offload_create(), io_register_iowq_max_workers()
and io_ring_exit_work().
Before the sq thread releases CPU resources, unlocking sqd->lock will
provide the user a better experience because it can respond quickly to
user requests.
Signed-off-by: Kanchan Joshi<[email protected]>
Signed-off-by: Wenwen Chen<[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
---
io_uring/sqpoll.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/io_uring/sqpoll.c b/io_uring/sqpoll.c
index 559652380672c..6ffa5cf1bbb86 100644
--- a/io_uring/sqpoll.c
+++ b/io_uring/sqpoll.c
@@ -256,9 +256,13 @@ static int io_sq_thread(void *data)
sqt_spin = true;
if (sqt_spin || !time_after(jiffies, timeout)) {
- cond_resched();
if (sqt_spin)
timeout = jiffies + sqd->sq_thread_idle;
+ if (unlikely(need_resched())) {
+ mutex_unlock(&sqd->lock);
+ cond_resched();
+ mutex_lock(&sqd->lock);
+ }
continue;
}
--
2.39.2
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