Re: [PATCH] SCSI: don't get target/host busy_count in scsi_mq_get_budget()

Jens Axboe
2017-11-08T02:55:32Z

On 11/07/2017 05:39 PM, Ming Lei wrote:
> On Tue, Nov 07, 2017 at 04:20:08PM +0000, Bart Van Assche wrote:
>> On Tue, 2017-11-07 at 10:11 +0800, Ming Lei wrote:
>>> If you can reproduce, please provide me at least the following log
>>> first:
>>>
>>> find /sys/kernel/debug/block -name tags | xargs cat | grep busy
>>>
>>> If any pending requests arn't completed, please provide the related
>>> info in dbgfs about where is the request.
>>
>> Every time I ran the above or a similar command its output was empty. I
>> assume that's because the hang usually occurs in a phase where these debugfs
>> attributes either have not yet been created or have already disappeared.
>
> Could you dump all tags? Then you can see if this attribute is disappeared.
>
> If that output is empty, it often means there isn't pending request not
> completed. So if that is true, your hang is _not_ related with RESTART.

You need to check sched_tags as well. It could still be a restart race
or problem, if tags is empty but sched_tags has busy bits.

--
Jens Axboe