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* [PATCH] io_uring: add more uring info to fdinfo for debug
@ 2021-09-13 13:08 Hao Xu
  2021-09-15 13:01 ` Hao Xu
  2021-09-15 15:26 ` Jens Axboe
  0 siblings, 2 replies; 6+ messages in thread
From: Hao Xu @ 2021-09-13 13:08 UTC (permalink / raw)
  To: Jens Axboe; +Cc: io-uring, Pavel Begunkov, Joseph Qi

Developers may need some uring info to help themselves debug and address
issues, these info includes sqring/cqring head/tail and the detail
sqe/cqe info, which is very useful when it stucks.

Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
---
 fs/io_uring.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 55 insertions(+), 4 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index f795ad281038..ac048592a3e8 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -9950,8 +9950,48 @@ static int io_uring_show_cred(struct seq_file *m, unsigned int id,
 static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m)
 {
 	struct io_sq_data *sq = NULL;
+	struct io_overflow_cqe *ocqe;
+	struct io_rings *r = ctx->rings;
+	unsigned int sq_mask = ctx->sq_entries - 1, cq_mask = ctx->cq_entries - 1;
+	unsigned int cached_sq_head = ctx->cached_sq_head;
+	unsigned int cached_cq_tail = ctx->cached_cq_tail;
+	unsigned int sq_head = READ_ONCE(r->sq.head);
+	unsigned int sq_tail = READ_ONCE(r->sq.tail);
+	unsigned int cq_head = READ_ONCE(r->cq.head);
+	unsigned int cq_tail = READ_ONCE(r->cq.tail);
 	bool has_lock;
-	int i;
+	unsigned int i;
+
+	/*
+	 * we may get imprecise sqe and cqe info if uring is actively running
+	 * since we get cached_sq_head and cached_cq_tail without uring_lock
+	 * and sq_tail and cq_head are changed by userspace. But it's ok since
+	 * we usually use these info when it is stuck.
+	 */
+	seq_printf(m, "SqHead:\t%u\n", sq_head & sq_mask);
+	seq_printf(m, "SqTail:\t%u\n", sq_tail & sq_mask);
+	seq_printf(m, "CachedSqHead:\t%u\n", cached_sq_head & sq_mask);
+	seq_printf(m, "CqHead:\t%u\n", cq_head & cq_mask);
+	seq_printf(m, "CqTail:\t%u\n", cq_tail & cq_mask);
+	seq_printf(m, "CachedCqTail:\t%u\n", cached_cq_tail & cq_mask);
+	seq_printf(m, "SQEs:\t%u\n", sq_tail - cached_sq_head);
+	for (i = cached_sq_head; i < sq_tail; i++) {
+		unsigned int sq_idx = READ_ONCE(ctx->sq_array[i & sq_mask]);
+
+		if (likely(sq_idx <= sq_mask)) {
+			struct io_uring_sqe *sqe = &ctx->sq_sqes[sq_idx];
+
+			seq_printf(m, "%5u: opcode:%d, fd:%d, flags:%x, user_data:%llu\n",
+				   sq_idx, sqe->opcode, sqe->fd, sqe->flags, sqe->user_data);
+		}
+	}
+	seq_printf(m, "CQEs:\t%u\n", cached_cq_tail - cq_head);
+	for (i = cq_head; i < cached_cq_tail; i++) {
+		struct io_uring_cqe *cqe = &r->cqes[i & cq_mask];
+
+		seq_printf(m, "%5u: user_data:%llu, res:%d, flag:%x\n",
+			   i & cq_mask, cqe->user_data, cqe->res, cqe->flags);
+	}
 
 	/*
 	 * Avoid ABBA deadlock between the seq lock and the io_uring mutex,
@@ -9993,7 +10033,10 @@ static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m)
 		xa_for_each(&ctx->personalities, index, cred)
 			io_uring_show_cred(m, index, cred);
 	}
-	seq_printf(m, "PollList:\n");
+	if (has_lock)
+		mutex_unlock(&ctx->uring_lock);
+
+	seq_puts(m, "PollList:\n");
 	spin_lock(&ctx->completion_lock);
 	for (i = 0; i < (1U << ctx->cancel_hash_bits); i++) {
 		struct hlist_head *list = &ctx->cancel_hash[i];
@@ -10003,9 +10046,17 @@ static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m)
 			seq_printf(m, "  op=%d, task_works=%d\n", req->opcode,
 					req->task->task_works != NULL);
 	}
+
+	seq_puts(m, "CqOverflowList:\n");
+	list_for_each_entry(ocqe, &ctx->cq_overflow_list, list) {
+		struct io_uring_cqe *cqe = &ocqe->cqe;
+
+		seq_printf(m, "  user_data=%llu, res=%d, flags=%x\n",
+			   cqe->user_data, cqe->res, cqe->flags);
+
+	}
+
 	spin_unlock(&ctx->completion_lock);
-	if (has_lock)
-		mutex_unlock(&ctx->uring_lock);
 }
 
 static void io_uring_show_fdinfo(struct seq_file *m, struct file *f)
-- 
2.24.4


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] io_uring: add more uring info to fdinfo for debug
  2021-09-13 13:08 [PATCH] io_uring: add more uring info to fdinfo for debug Hao Xu
@ 2021-09-15 13:01 ` Hao Xu
  2021-09-15 15:26 ` Jens Axboe
  1 sibling, 0 replies; 6+ messages in thread
From: Hao Xu @ 2021-09-15 13:01 UTC (permalink / raw)
  To: Jens Axboe; +Cc: io-uring, Pavel Begunkov, Joseph Qi

ping...
在 2021/9/13 下午9:08, Hao Xu 写道:
> Developers may need some uring info to help themselves debug and address
> issues, these info includes sqring/cqring head/tail and the detail
> sqe/cqe info, which is very useful when it stucks.
> 
> Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
> ---
>   fs/io_uring.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++----
>   1 file changed, 55 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index f795ad281038..ac048592a3e8 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -9950,8 +9950,48 @@ static int io_uring_show_cred(struct seq_file *m, unsigned int id,
>   static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m)
>   {
>   	struct io_sq_data *sq = NULL;
> +	struct io_overflow_cqe *ocqe;
> +	struct io_rings *r = ctx->rings;
> +	unsigned int sq_mask = ctx->sq_entries - 1, cq_mask = ctx->cq_entries - 1;
> +	unsigned int cached_sq_head = ctx->cached_sq_head;
> +	unsigned int cached_cq_tail = ctx->cached_cq_tail;
> +	unsigned int sq_head = READ_ONCE(r->sq.head);
> +	unsigned int sq_tail = READ_ONCE(r->sq.tail);
> +	unsigned int cq_head = READ_ONCE(r->cq.head);
> +	unsigned int cq_tail = READ_ONCE(r->cq.tail);
>   	bool has_lock;
> -	int i;
> +	unsigned int i;
> +
> +	/*
> +	 * we may get imprecise sqe and cqe info if uring is actively running
> +	 * since we get cached_sq_head and cached_cq_tail without uring_lock
> +	 * and sq_tail and cq_head are changed by userspace. But it's ok since
> +	 * we usually use these info when it is stuck.
> +	 */
> +	seq_printf(m, "SqHead:\t%u\n", sq_head & sq_mask);
> +	seq_printf(m, "SqTail:\t%u\n", sq_tail & sq_mask);
> +	seq_printf(m, "CachedSqHead:\t%u\n", cached_sq_head & sq_mask);
> +	seq_printf(m, "CqHead:\t%u\n", cq_head & cq_mask);
> +	seq_printf(m, "CqTail:\t%u\n", cq_tail & cq_mask);
> +	seq_printf(m, "CachedCqTail:\t%u\n", cached_cq_tail & cq_mask);
> +	seq_printf(m, "SQEs:\t%u\n", sq_tail - cached_sq_head);
> +	for (i = cached_sq_head; i < sq_tail; i++) {
> +		unsigned int sq_idx = READ_ONCE(ctx->sq_array[i & sq_mask]);
> +
> +		if (likely(sq_idx <= sq_mask)) {
> +			struct io_uring_sqe *sqe = &ctx->sq_sqes[sq_idx];
> +
> +			seq_printf(m, "%5u: opcode:%d, fd:%d, flags:%x, user_data:%llu\n",
> +				   sq_idx, sqe->opcode, sqe->fd, sqe->flags, sqe->user_data);
> +		}
> +	}
> +	seq_printf(m, "CQEs:\t%u\n", cached_cq_tail - cq_head);
> +	for (i = cq_head; i < cached_cq_tail; i++) {
> +		struct io_uring_cqe *cqe = &r->cqes[i & cq_mask];
> +
> +		seq_printf(m, "%5u: user_data:%llu, res:%d, flag:%x\n",
> +			   i & cq_mask, cqe->user_data, cqe->res, cqe->flags);
> +	}
>   
>   	/*
>   	 * Avoid ABBA deadlock between the seq lock and the io_uring mutex,
> @@ -9993,7 +10033,10 @@ static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m)
>   		xa_for_each(&ctx->personalities, index, cred)
>   			io_uring_show_cred(m, index, cred);
>   	}
> -	seq_printf(m, "PollList:\n");
> +	if (has_lock)
> +		mutex_unlock(&ctx->uring_lock);
> +
> +	seq_puts(m, "PollList:\n");
>   	spin_lock(&ctx->completion_lock);
>   	for (i = 0; i < (1U << ctx->cancel_hash_bits); i++) {
>   		struct hlist_head *list = &ctx->cancel_hash[i];
> @@ -10003,9 +10046,17 @@ static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m)
>   			seq_printf(m, "  op=%d, task_works=%d\n", req->opcode,
>   					req->task->task_works != NULL);
>   	}
> +
> +	seq_puts(m, "CqOverflowList:\n");
> +	list_for_each_entry(ocqe, &ctx->cq_overflow_list, list) {
> +		struct io_uring_cqe *cqe = &ocqe->cqe;
> +
> +		seq_printf(m, "  user_data=%llu, res=%d, flags=%x\n",
> +			   cqe->user_data, cqe->res, cqe->flags);
> +
> +	}
> +
>   	spin_unlock(&ctx->completion_lock);
> -	if (has_lock)
> -		mutex_unlock(&ctx->uring_lock);
>   }
>   
>   static void io_uring_show_fdinfo(struct seq_file *m, struct file *f)
> 


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] io_uring: add more uring info to fdinfo for debug
  2021-09-13 13:08 [PATCH] io_uring: add more uring info to fdinfo for debug Hao Xu
  2021-09-15 13:01 ` Hao Xu
@ 2021-09-15 15:26 ` Jens Axboe
  2021-09-15 15:31   ` Pavel Begunkov
  1 sibling, 1 reply; 6+ messages in thread
From: Jens Axboe @ 2021-09-15 15:26 UTC (permalink / raw)
  To: Hao Xu; +Cc: io-uring, Pavel Begunkov, Joseph Qi

On 9/13/21 7:08 AM, Hao Xu wrote:
> Developers may need some uring info to help themselves debug and address
> issues, these info includes sqring/cqring head/tail and the detail
> sqe/cqe info, which is very useful when it stucks.

I think this is a good addition, more info to help you debug a stuck case
is always good. I'll queue this up for 5.16.

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] io_uring: add more uring info to fdinfo for debug
  2021-09-15 15:26 ` Jens Axboe
@ 2021-09-15 15:31   ` Pavel Begunkov
  2021-09-15 15:32     ` Jens Axboe
  0 siblings, 1 reply; 6+ messages in thread
From: Pavel Begunkov @ 2021-09-15 15:31 UTC (permalink / raw)
  To: Jens Axboe, Hao Xu; +Cc: io-uring, Joseph Qi

On 9/15/21 4:26 PM, Jens Axboe wrote:
> On 9/13/21 7:08 AM, Hao Xu wrote:
>> Developers may need some uring info to help themselves debug and address
>> issues, these info includes sqring/cqring head/tail and the detail
>> sqe/cqe info, which is very useful when it stucks.
> 
> I think this is a good addition, more info to help you debug a stuck case
> is always good. I'll queue this up for 5.16.

Are there limits how much we can print? I remember people were couldn't
even show a list of CPUs (was it proc?). The overflow list may be huge.

-- 
Pavel Begunkov

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] io_uring: add more uring info to fdinfo for debug
  2021-09-15 15:31   ` Pavel Begunkov
@ 2021-09-15 15:32     ` Jens Axboe
  2021-09-16  6:29       ` Hao Xu
  0 siblings, 1 reply; 6+ messages in thread
From: Jens Axboe @ 2021-09-15 15:32 UTC (permalink / raw)
  To: Pavel Begunkov, Hao Xu; +Cc: io-uring, Joseph Qi

On 9/15/21 9:31 AM, Pavel Begunkov wrote:
> On 9/15/21 4:26 PM, Jens Axboe wrote:
>> On 9/13/21 7:08 AM, Hao Xu wrote:
>>> Developers may need some uring info to help themselves debug and address
>>> issues, these info includes sqring/cqring head/tail and the detail
>>> sqe/cqe info, which is very useful when it stucks.
>>
>> I think this is a good addition, more info to help you debug a stuck case
>> is always good. I'll queue this up for 5.16.
> 
> Are there limits how much we can print? I remember people were couldn't
> even show a list of CPUs (was it proc?). The overflow list may be huge.

It's using seq_file, so I _think_ we should be fine here. Not sure when/if
it truncates.

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] io_uring: add more uring info to fdinfo for debug
  2021-09-15 15:32     ` Jens Axboe
@ 2021-09-16  6:29       ` Hao Xu
  0 siblings, 0 replies; 6+ messages in thread
From: Hao Xu @ 2021-09-16  6:29 UTC (permalink / raw)
  To: Jens Axboe, Pavel Begunkov; +Cc: io-uring, Joseph Qi

在 2021/9/15 下午11:32, Jens Axboe 写道:
> On 9/15/21 9:31 AM, Pavel Begunkov wrote:
>> On 9/15/21 4:26 PM, Jens Axboe wrote:
>>> On 9/13/21 7:08 AM, Hao Xu wrote:
>>>> Developers may need some uring info to help themselves debug and address
>>>> issues, these info includes sqring/cqring head/tail and the detail
>>>> sqe/cqe info, which is very useful when it stucks.
>>>
>>> I think this is a good addition, more info to help you debug a stuck case
>>> is always good. I'll queue this up for 5.16.
>>
>> Are there limits how much we can print? I remember people were couldn't
>> even show a list of CPUs (was it proc?). The overflow list may be huge.
> 
> It's using seq_file, so I _think_ we should be fine here. Not sure when/if
> it truncates.
> 
It seems the default buf size of seq_file is PAGE_SIZE.


^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2021-09-16  6:29 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-09-13 13:08 [PATCH] io_uring: add more uring info to fdinfo for debug Hao Xu
2021-09-15 13:01 ` Hao Xu
2021-09-15 15:26 ` Jens Axboe
2021-09-15 15:31   ` Pavel Begunkov
2021-09-15 15:32     ` Jens Axboe
2021-09-16  6:29       ` Hao Xu

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