linux-kernel - Re: [PATCH v9] io_uring: Statistics of the true utilization of sq threads.

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Date: Wed, 21 Feb 2024 10:04:27 +0800
From: Xiaobing Li <xiaobing.li@...sung.com>
To: axboe@...nel.dk
Cc: asml.silence@...il.com, linux-kernel@...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@...sung.com, cliang01.li@...sung.com,
	xue01.he@...sung.com
Subject: Re: [PATCH v9] io_uring: Statistics of the true utilization of sq
 threads.

On 2/19/24 14:42, Xiaobing Li wrote:
>diff --git a/io_uring/fdinfo.c b/io_uring/fdinfo.c
>index 976e9500f651..37afc5bac279 100644
>--- a/io_uring/fdinfo.c
>+++ b/io_uring/fdinfo.c
>@@ -55,6 +55,7 @@ __cold void io_uring_show_fdinfo(struct seq_file *m, struct file *f)
> 	struct io_ring_ctx *ctx = f->private_data;
> 	struct io_overflow_cqe *ocqe;
> 	struct io_rings *r = ctx->rings;
>+	struct rusage sq_usage;
> 	unsigned int sq_mask = ctx->sq_entries - 1, cq_mask = ctx->cq_entries - 1;
> 	unsigned int sq_head = READ_ONCE(r->sq.head);
> 	unsigned int sq_tail = READ_ONCE(r->sq.tail);
>@@ -64,6 +65,7 @@ __cold void io_uring_show_fdinfo(struct seq_file *m, struct file *f)
> 	unsigned int sq_shift = 0;
> 	unsigned int sq_entries, cq_entries;
> 	int sq_pid = -1, sq_cpu = -1;
>+	u64 sq_total_time = 0, sq_work_time = 0;
> 	bool has_lock;
> 	unsigned int i;
> 
>@@ -147,10 +149,15 @@ __cold void io_uring_show_fdinfo(struct seq_file *m, struct file *f)
> 
> 		sq_pid = sq->task_pid;
> 		sq_cpu = sq->sq_cpu;
>+		getrusage(sq->thread, RUSAGE_SELF, &sq_usage);
>+		sq_total_time = sq_usage.ru_stime.tv_sec * 1000000 + sq_usage.ru_stime.tv_usec;
>+		sq_work_time = sq->work_time;
> 	}
> 
> 	seq_printf(m, "SqThread:\t%d\n", sq_pid);
> 	seq_printf(m, "SqThreadCpu:\t%d\n", sq_cpu);
>+	seq_printf(m, "SqTotalTime:\t%llu\n", sq_total_time);
>+	seq_printf(m, "SqWorkTime:\t%llu\n", sq_work_time);
> 	seq_printf(m, "UserFiles:\t%u\n", ctx->nr_user_files);
> 	for (i = 0; has_lock && i < ctx->nr_user_files; i++) {
> 		struct file *f = io_file_from_index(&ctx->file_table, i);
>diff --git a/io_uring/sqpoll.c b/io_uring/sqpoll.c
>index 65b5dbe3c850..006d7fc9cf92 100644
>--- a/io_uring/sqpoll.c
>+++ b/io_uring/sqpoll.c
>@@ -219,10 +219,22 @@ static bool io_sqd_handle_event(struct io_sq_data *sqd)
> 	return did_sig || test_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state);
> }
> 
>+static void io_sq_update_worktime(struct io_sq_data *sqd, struct rusage *start)
>+{
>+		struct rusage end;
>+
>+		getrusage(current, RUSAGE_SELF, &end);
>+		end.ru_stime.tv_sec -= start->ru_stime.tv_sec;
>+		end.ru_stime.tv_usec -= start->ru_stime.tv_usec;
>+
>+		sqd->work_time += end.ru_stime.tv_usec + end.ru_stime.tv_sec * 1000000;
>+}
>+
> static int io_sq_thread(void *data)
> {
> 	struct io_sq_data *sqd = data;
> 	struct io_ring_ctx *ctx;
>+	struct rusage start;
> 	unsigned long timeout = 0;
> 	char buf[TASK_COMM_LEN];
> 	DEFINE_WAIT(wait);
>@@ -251,6 +263,7 @@ static int io_sq_thread(void *data)
> 		}
> 
> 		cap_entries = !list_is_singular(&sqd->ctx_list);
>+		getrusage(current, RUSAGE_SELF, &start);
> 		list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) {
> 			int ret = __io_sq_thread(ctx, cap_entries);
> 
>@@ -261,8 +274,10 @@ static int io_sq_thread(void *data)
> 			sqt_spin = true;
> 
> 		if (sqt_spin || !time_after(jiffies, timeout)) {
>-			if (sqt_spin)
>+			if (sqt_spin) {
>+				io_sq_update_worktime(sqd, &start);
> 				timeout = jiffies + sqd->sq_thread_idle;
>+			}
> 			if (unlikely(need_resched())) {
> 				mutex_unlock(&sqd->lock);
> 				cond_resched();
>diff --git a/io_uring/sqpoll.h b/io_uring/sqpoll.h
>index 8df37e8c9149..4171666b1cf4 100644
>--- a/io_uring/sqpoll.h
>+++ b/io_uring/sqpoll.h
>@@ -16,6 +16,7 @@ struct io_sq_data {
> 	pid_t			task_pid;
> 	pid_t			task_tgid;
> 
>+	u64			work_time;
> 	unsigned long		state;
> 	struct completion	exited;
> };
 
Hi, Jens
I have modified the code according to your suggestions.
Do you have any other comments?

--
Xiaobing Li