linux-kernel - [PATCH 3/3] IO_URING: Statistics of the true utilization of sq threads.

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Date:   Thu, 28 Sep 2023 10:22:28 +0800
From:   Xiaobing Li <xiaobing.li@...sung.com>
To:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com, axboe@...nel.dk,
        asml.silence@...il.com
Cc:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        io-uring@...r.kernel.org, kun.dou@...sung.com,
        peiwei.li@...sung.com, joshi.k@...sung.com,
        kundan.kumar@...sung.com, wenwen.chen@...sung.com,
        ruyi.zhang@...sung.com, Xiaobing Li <xiaobing.li@...sung.com>
Subject: [PATCH 3/3] IO_URING: Statistics of the true utilization of sq
 threads.

Since the sq thread has a while(1) structure, during this process, there
may be a lot of time that is not processing IO but does not exceed the
timeout period, therefore, the sqpoll thread will keep running and will
keep occupying the CPU. Obviously, the CPU is wasted at this time;Our
goal is to count the part of the time that the sqpoll thread actually
processes IO, so as to reflect the part of the CPU it uses to process
IO, which can be used to help improve the actual utilization of the CPU
in the future.

Signed-off-by: Xiaobing Li <xiaobing.li@...sung.com>
---
 io_uring/sqpoll.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/io_uring/sqpoll.c b/io_uring/sqpoll.c
index bd6c2c7959a5..2c5fc4d95fa8 100644
--- a/io_uring/sqpoll.c
+++ b/io_uring/sqpoll.c
@@ -11,6 +11,7 @@
 #include <linux/audit.h>
 #include <linux/security.h>
 #include <linux/io_uring.h>
+#include <linux/time.h>
 
 #include <uapi/linux/io_uring.h>
 
@@ -235,6 +236,10 @@ static int io_sq_thread(void *data)
 		set_cpus_allowed_ptr(current, cpu_online_mask);
 
 	mutex_lock(&sqd->lock);
+	bool first = true;
+	struct timespec64 ts_start, ts_end;
+	struct timespec64 ts_delta;
+	struct sched_entity *se = &sqd->thread->se;
 	while (1) {
 		bool cap_entries, sqt_spin = false;
 
@@ -243,7 +248,16 @@ static int io_sq_thread(void *data)
 				break;
 			timeout = jiffies + sqd->sq_thread_idle;
 		}
-
+		ktime_get_boottime_ts64(&ts_start);
+		ts_delta = timespec64_sub(ts_start, ts_end);
+		unsigned long long now = ts_delta.tv_sec * NSEC_PER_SEC + ts_delta.tv_nsec +
+		se->sq_avg.last_update_time;
+
+		if (first) {
+			now = 0;
+			first = false;
+		}
+		__update_sq_avg_block(now, se);
 		cap_entries = !list_is_singular(&sqd->ctx_list);
 		list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) {
 			int ret = __io_sq_thread(ctx, cap_entries);
@@ -251,6 +265,16 @@ static int io_sq_thread(void *data)
 			if (!sqt_spin && (ret > 0 || !wq_list_empty(&ctx->iopoll_list)))
 				sqt_spin = true;
 		}
+
+		ktime_get_boottime_ts64(&ts_end);
+		ts_delta = timespec64_sub(ts_end, ts_start);
+		now = ts_delta.tv_sec * NSEC_PER_SEC + ts_delta.tv_nsec +
+		se->sq_avg.last_update_time;
+
+		if (sqt_spin)
+			__update_sq_avg(now, se);
+		else
+			__update_sq_avg_block(now, se);
 		if (io_run_task_work())
 			sqt_spin = true;
 
-- 
2.34.1