Date: Sat, 3 Oct 2009 19:51:41 +0200
From: Jens Axboe <jens.axboe@oracle.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>, Vivek Goyal <vgoyal@redhat.com>,
       Ingo Molnar <mingo@elte.hu>,
       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,
       riel@redhat.com
Subject: Re: Do not overload dispatch queue (Was: Re: IO scheduler based IO
	controller V10)
Message-ID: <20091003175141.GH31616@kernel.dk>
References: <20091003124049.GB12925@redhat.com> <20091003132115.GB31616@kernel.dk> <20091003135623.GD12925@redhat.com> <1254578553.7499.5.camel@marge.simson.net> <20091003142840.GE31616@kernel.dk> <1254581496.8293.8.camel@marge.simson.net> <20091003151445.GF31616@kernel.dk> <1254585420.7539.2.camel@marge.simson.net> <20091003173532.GG31616@kernel.dk> <alpine.LFD.2.01.0910031042560.6996@localhost.localdomain>
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On Sat, Oct 03 2009, Linus Torvalds wrote:
> 
> 
> On Sat, 3 Oct 2009, Jens Axboe wrote:
> > 
> > Doesn't look too bad, all things considered. Apart from "stock" cfq,
> > it's consistent. And being consistent is a Good Thing. Performance wise,
> > it's losing out to "stock" but looks pretty competetive otherwise.
> 
> I agree. And I think the numbers for the kconsole test are pretty 
> conclusive. That's a big improvement (on top of the already very 
> impressive improvement).

Yes very much so. The tweaks are mostly straight forward, so my
confidence in the end results from a "will this work" stand point is
good. It will likely be somewhat slower for some things, but we can fix
those up as we continue testing.

I wont ask you to pull this yet, but I likely will next week when I've
done some benchmarks with it for the other end of the spectrum.

> > So far that looks like a winner. The dictator wanted good latency, he's
> > getting good latency. I'll continue working on this on monday, while I'm
> > waiting for delivery of the Trabant.
> 
> Trabant?
> 
> As in the car? 
> 
> Why would you _ever_ wait for delivery? The sane option would be to try to 
> hide, or run away?

OK, so I'm not really waiting for a Trabant. I do have a car on order,
but not a 2-stroke :-)

-- 
Jens Axboe

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