From 533ab73f5b5c95dcb4152b52d5482abcc824c690 Mon Sep 17 00:00:00 2001 From: Wenwen Chen Date: Thu, 25 May 2023 16:26:26 +0800 Subject: 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 Signed-off-by: Wenwen Chen Link: https://lore.kernel.org/r/20230525082626.577862-1-wenwen.chen@samsung.com Signed-off-by: Jens Axboe --- 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 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; } -- cgit v1.2.3