Bart Van Assche <[email protected]> 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.
