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| author | Wenwen Chen <wenwen.chen@samsung.com> | 2023-05-25 16:26:26 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2023-05-25 09:30:13 -0600 |
| commit | 533ab73f5b5c95dcb4152b52d5482abcc824c690 (patch) | |
| tree | 8214f20ed59dc84edeef2f7cf54c7b218c9b3cd4 | |
| parent | 293007b033418c8c9d1b35d68dec49a500750fde (diff) | |
| download | lwn-533ab73f5b5c95dcb4152b52d5482abcc824c690.tar.gz lwn-533ab73f5b5c95dcb4152b52d5482abcc824c690.zip | |
io_uring: unlock sqd->lock before sq thread release CPU
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<joshi.k@samsung.com>
Signed-off-by: Wenwen Chen<wenwen.chen@samsung.com>
Link: https://lore.kernel.org/r/20230525082626.577862-1-wenwen.chen@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | io_uring/sqpoll.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/io_uring/sqpoll.c b/io_uring/sqpoll.c index 9db4bc1f521a..5e329e3cd470 100644 --- a/io_uring/sqpoll.c +++ b/io_uring/sqpoll.c @@ -255,9 +255,13 @@ 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; } |