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From: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
To: Corrado Zoccolo <czoccolo@gmail.com>
Cc: "jmoyer@redhat.com" <jmoyer@redhat.com>,
	Jens Axboe <jens.axboe@oracle.com>,
	Shaohua Li <shaohua.li@intel.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: fio mmap randread 64k more than 40% regression with 2.6.33-rc1
Date: Mon, 18 Jan 2010 11:06:38 +0800	[thread overview]
Message-ID: <1263783999.12893.2.camel@localhost> (raw)
In-Reply-To: <4e5e476b1001160827n6dc73b35vee8b46e541134c2@mail.gmail.com>

On Sat, 2010-01-16 at 17:27 +0100, Corrado Zoccolo wrote:
> Hi Yanmin
> On Mon, Jan 4, 2010 at 7:28 PM, Corrado Zoccolo <czoccolo@gmail.com> wrote:
> > Hi Yanmin,
> >> When low_latency=1, we get the biggest number with kernel 2.6.32.
> >> Comparing with low_latency=0's result, the prior one is about 4% better.
> > Ok, so 2.6.33 + corrado (with low_latency =0) is comparable with
> > fastest 2.6.32, so we can consider the first part of the problem
> > solved.
> >
> I think we can return now to your full script with queue merging.
> I'm wondering if (in arm_slice_timer):
> -       if (cfqq->dispatched)
> +      if (cfqq->dispatched || (cfqq->new_cfqq && rq_in_driver(cfqd)))
>                return;
> gives the same improvement you were experiencing just reverting to rq_in_driver.
I did a quick testing against 2.6.33-rc1. With the new method, fio mmap randread 46k
has about 20% improvement. With just checking rq_in_driver(cfqd), it has
about 33% improvement.


> 
> We saw that cfqq->dispatched worked fine when there was no queue
> merging happening, so it must be something concerning merging,
> probably dispatched is not accurate when we set up for a merging, but
> the merging was not yet done.



  reply	other threads:[~2010-01-18  3:04 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-12-31  9:16 fio mmap randread 64k more than 40% regression with 2.6.33-rc1 Zhang, Yanmin
2009-12-31 10:34 ` Corrado Zoccolo
2010-01-01 10:12   ` Zhang, Yanmin
2010-01-01 16:32     ` Corrado Zoccolo
2010-01-02 12:33       ` Zhang, Yanmin
2010-01-02 18:52         ` Corrado Zoccolo
2010-01-04  8:18           ` Zhang, Yanmin
2010-01-04 18:28             ` Corrado Zoccolo
2010-01-16 16:27               ` Corrado Zoccolo
2010-01-18  3:06                 ` Zhang, Yanmin [this message]
2010-01-19 20:10                   ` Corrado Zoccolo
2010-01-19 20:42                     ` Jeff Moyer
2010-01-19 21:40                     ` Vivek Goyal
2010-01-19 21:58                       ` Corrado Zoccolo
2010-01-20 19:18                         ` Vivek Goyal
2010-01-20  1:29                       ` Shaohua Li
2010-01-20 14:00                         ` Jeff Moyer

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