On 03/03/11 23:08, Jan Kara wrote: > On Thu 03-03-11 21:31:19, Wu Fengguang wrote: >> On Thu, Mar 03, 2011 at 10:26:19AM +0800, Jun'ichi Nomura wrote: >> > flush-8:0-2743 4606: block_bio_queue: 8,0 W 94899962 + 8 >> > flush-8:0-2743 4606: block_bio_queue: 8,0 W 94899970 + 8 >> > flush-8:0-2743 4606: block_bio_queue: 8,0 W 94899978 + 8 >> > flush-8:0-2743 4606: block_bio_queue: 8,0 W 94899986 + 8 >> > flush-8:0-2743 4606: block_bio_queue: 8,0 W 94899994 + 8 >> ==> > kworker/0:1-11 4606: block_rq_issue: 8,0 W 0 () 94899962 + 40 >> > >> flush-8:0-2743 4606: block_bio_queue: 8,0 W 94898554 + 8 >> ==> > >> flush-8:0-2743 4606: block_rq_issue: 8,0 W 0 () 94898554 + 8 >> >> I'd expect the wrapped around 94898554+8 to be merged with 94899962+8. > How could they be merged? They are not continguous... > >> Why kworker/0:1-11 is submitting the request early? And the second >> request is submitted by flush-8:0-2743. > I'm not sure about that either - but I think that kworker is submitting > the work when unplug happens while flush ends up doing it when the queue is > alredy unplugged. Yes. For the above case, it was unplug. For other cases, the reason was max_sectors. Before writeback wraps around, the request has already grown to max_sectors size (~512KB) and doesn't accept new merge. Thanks, -- Jun'ichi Nomura, NEC Corporation -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
