Messages in this thread | | | Date | Mon, 14 Jan 2013 10:22:33 -0500 | From | Vivek Goyal <> | Subject | Re: Re: [PATCH] blkcg: Before starting a new slice, firstly count bps/iops limit in func tg_may_dispatch. |
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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
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