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* [PATCH RESEND] io_uring: show sqthread pid and cpu in fdinfo
@ 2020-09-24  2:55 Joseph Qi
  2020-09-24 10:04 ` Stefano Garzarella
  2020-09-24 19:49 ` Jens Axboe
  0 siblings, 2 replies; 3+ messages in thread
From: Joseph Qi @ 2020-09-24  2:55 UTC (permalink / raw)
  To: Jens Axboe; +Cc: io-uring, Xiaoguang Wang

In most cases we'll specify IORING_SETUP_SQPOLL and run multiple
io_uring instances in a host. Since all sqthreads are named
"io_uring-sq", it's hard to distinguish the relations between
application process and its io_uring sqthread.
With this patch, application can get its corresponding sqthread pid
and cpu through show_fdinfo.
Steps:
1. Get io_uring fd first.
$ ls -l /proc/<pid>/fd | grep -w io_uring
2. Then get io_uring instance related info, including corresponding
sqthread pid and cpu.
$ cat /proc/<pid>/fdinfo/<io_uring_fd>

pos:	0
flags:	02000002
mnt_id:	13
SqThread:	6929
SqThreadCpu:	2
UserFiles:	1
    0: testfile
UserBufs:	0
PollList:

Signed-off-by: Joseph Qi <[email protected]>
---
 fs/io_uring.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 8b426aa..9c8b3b3 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8415,6 +8415,10 @@ static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m)
 	int i;
 
 	mutex_lock(&ctx->uring_lock);
+	seq_printf(m, "SqThread:\t%d\n", (ctx->flags & IORING_SETUP_SQPOLL) ?
+					 task_pid_nr(ctx->sqo_thread) : -1);
+	seq_printf(m, "SqThreadCpu:\t%d\n", (ctx->flags & IORING_SETUP_SQPOLL) ?
+					    task_cpu(ctx->sqo_thread) : -1);
 	seq_printf(m, "UserFiles:\t%u\n", ctx->nr_user_files);
 	for (i = 0; i < ctx->nr_user_files; i++) {
 		struct fixed_file_table *table;
-- 
1.8.3.1


^ permalink raw reply related	[flat|nested] 3+ messages in thread

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2020-09-24  2:55 [PATCH RESEND] io_uring: show sqthread pid and cpu in fdinfo Joseph Qi
2020-09-24 10:04 ` Stefano Garzarella
2020-09-24 19:49 ` Jens Axboe

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