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

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Message-ID: <0d0fda8f-36c1-49f4-aef0-527a79a34448@kernel.dk>
Date: Wed, 21 Feb 2024 10:28:54 -0700
From: Jens Axboe <axboe@...nel.dk>
To: Xiaobing Li <xiaobing.li@...sung.com>
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, cliang01.li@...sung.com, xue01.he@...sung.com
Subject: Re: [PATCH v9] io_uring: Statistics of the true utilization of sq
 threads.

On 2/20/24 7:04 PM, Xiaobing Li wrote:
> 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?

Out of town this week, I'll check next week. But from a quick look,
looks much better now.

-- 
Jens Axboe