Bart Van Assche <bvanassche@xxxxxxx> 于2018年12月5日周三 下午11:59写道：
>
> On Wed, 2018-12-05 at 23:37 +0800, Weiping Zhang wrote:
> > @@ -130,7 +119,7 @@ void blk_add_timer(struct request *req)
> > * than an existing one, modify the timer. Round up to next nearest
> > * second.
> > */
> > - expiry = blk_rq_timeout(round_jiffies_up(expiry));
> > + expiry = round_jiffies_up(expiry);
>
> If you would have read the comment above this code, you would have known
> that this patch does not do what you think it does and additionally that
> it introduces a regression.
>
Let's paste full comments here:
/*
* If the timer isn't already pending or this timeout is earlier
* than an existing one, modify the timer. Round up to next nearest
* second.
*/
Before this patch, even we set io_timeout to 30*HZ(default), but
blk_rq_timeout always return jiffies +5*HZ,
[1]. if there no pending request in timeout list, the timer callback
blk_rq_timed_out_timer will be called after 5*HZ, and then
blk_mq_check_expired will check is there exist some request
was delayed by compare jiffies and request->deadline, obvious
request is not timeout because we set request's timeouts is 30*HZ.
So for this case timer callback should be called at jiffies + 30 instead
of jiffies + 5*HZ.
[2]. if there are pending request in timeout list, we compare request's
expiry and queue's expiry. If time_after(request->expire, queue->expire) modify
queue->timeout.expire to request->expire, otherwise do nothing.
So I think this patch just solve problem in [1], no other regression, or what's
I missing here ?
Thanks
Weiping
> Bart.
