Subject: Re: IO scheduler based IO controller V10
From: Mike Galbraith <efault@gmx.de>
To: Jens Axboe <jens.axboe@oracle.com>
Cc: Vivek Goyal <vgoyal@redhat.com>,
       Ulrich Lukas <stellplatz-nr.13a@datenparkplatz.de>,
       linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org,
       dm-devel@redhat.com, nauman@google.com, dpshah@google.com,
       lizf@cn.fujitsu.com, mikew@google.com, fchecconi@gmail.com,
       paolo.valente@unimore.it, ryov@valinux.co.jp, fernando@oss.ntt.co.jp,
       jmoyer@redhat.com, dhaval@linux.vnet.ibm.com, balbir@linux.vnet.ibm.com,
       righi.andrea@gmail.com, m-ikeda@ds.jp.nec.com, agk@redhat.com,
       akpm@linux-foundation.org, peterz@infradead.org, jmarchan@redhat.com,
       torvalds@linux-foundation.org, mingo@elte.hu, riel@redhat.com
In-Reply-To: <20091002180857.GM31616@kernel.dk>
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Date: Fri, 02 Oct 2009 20:29:57 +0200
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On Fri, 2009-10-02 at 20:08 +0200, Jens Axboe wrote:
> On Thu, Oct 01 2009, Mike Galbraith wrote:
> >  	max_dispatch = cfqd->cfq_quantum;
> >  	if (cfq_class_idle(cfqq))
> >  		max_dispatch = 1;
> >  
> > +	if (cfqd->busy_queues > 1)
> > +		cfqd->od_stamp = jiffies;
> > +
> 
> ->busy_queues > 1 just means that they have requests ready for dispatch,
> not that they are dispatched.

But we're not alone, somebody else is using disk.  I'm trying to make
sure we don't have someone _about_ to come back.. like a reader, so when
there's another player, stamp to give him some time to wake up/submit
before putting the pedal to the metal.

	-Mike

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