>On Mon, Jan 14, 2013 at 10:15:58AM +0800, majianpeng wrote:
>
>[..]
>> >Index: linux-2.6/block/blk-throttle.c
>> >===================================================================
>> >--- linux-2.6.orig/block/blk-throttle.c 2012-10-18 01:52:28.000000000
>> >-0400
>> >+++ linux-2.6/block/blk-throttle.c 2013-01-14 03:40:41.355731375 -0500
>> >@@ -648,8 +648,14 @@ static bool tg_may_dispatch(struct throt
>> > * If previous slice expired, start a new one otherwise renew/extend
>> > * existing slice to make sure it is at least throtl_slice interval
>> > * long since now.
>> >+ *
>> >+ * Start a new slice only if there is no bio queued in that direction.
>> >+ * That bio is waiting to be dispatched and slice needs to be
>> >+ * extended. It might happen that bio waited to be dispatched but
>> >+ * workqueue execution got little late it might restart a new slice
>> >+ * instead of taking all the waited time into account.
>> > */
>> >- if (throtl_slice_used(td, tg, rw))
>> >+ if (throtl_slice_used(td, tg, rw) && !tg->nr_queued[rw])
>> > throtl_start_new_slice(td, tg, rw);
>> > else {
>> > if (time_before(tg->slice_end[rw], jiffies + throtl_slice))
>> Hi vivek,
>> Your patch is ok.But i had a question:
>> What's condition tg->nr_queued[rw] = 0, but bio is not null?
>
>When a new bio is about to be queued in an empty group (look at
>blk_throtl_bio). At that time, tg->nr_queued[rw] might be 0 if no other
>bio is already queued.
>
>Thanks
>Vivek
I see. Thanks your time!
Jianpeng
Thanks!
