linux-kernel - Re: [PATCH 0/3]CFQ: add think time check for service tree and group

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Message-ID: <20110711130520.GA30674@redhat.com>
Date:	Mon, 11 Jul 2011 09:05:20 -0400
From:	Vivek Goyal <vgoyal@...hat.com>
To:	Shaohua Li <shaohua.li@...el.com>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	Jens Axboe <jaxboe@...ionio.com>
Subject: Re: [PATCH 0/3]CFQ: add think time check for service tree and group

On Mon, Jul 11, 2011 at 01:44:05PM +0800, Shaohua Li wrote:
> 2011/7/4 Shaohua Li <shaohua.li@...el.com>:
> > Hi,
> >  Currently when the last queue of a service tree/group is empty, CFQ
> > doesn't expire the queue. This is to allow requests from the tree/group
> > come soon, so tree/group doesn't miss its share. But if the think time
> > is big, the assumption isn't correct. idling the queue is just wasting
> > bandwidth.
> >
> > Originally I was hoping this can resolve Vivek's fsync issue, but it
> > doesn't. The fsync issue is caused by queue idling. But since think time
> > check only helps for think time above default queue idle time (8ms),
> > think time check doesn't help.
> >
> > On the other hand, think time check is still helpful for queues with
> > think time. I had test case in follow patches show throughput
> > improvement without sacrifice tree/group shares.
> >
> Jens,
> can you look at the patches? I refreshed some patches in replying
> Vivek, I can resend if required.

Yep, please resend. That would be easier.

Thanks
Vivek
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