Subject: Re: Mysterious CFQ crash and RCU
From: Paul Bolle <pebolle@tiscali.nl>
To: Jens Axboe <jaxboe@fusionio.com>
Cc: "paulmck@linux.vnet.ibm.com" <paulmck@linux.vnet.ibm.com>,
        Vivek Goyal <vgoyal@redhat.com>,
        linux kernel mailing list <linux-kernel@vger.kernel.org>
Date: Wed, 25 May 2011 11:40:25 +0200
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On Wed, 2011-05-25 at 11:30 +0200, Jens Axboe wrote:
> If you build CFQ modular, then all you have to do is switch to using CFQ
> before starting your testing:
> 
> # echo cfq > /sys/block/sda/queue/scheduler
> 
> and switch sda to eg noop before you can remove cfq-iosched again. As
> long as things crash, then you wont be able to remove cfq anyway and you
> have to reboot to test something new anyway. So the modular nature of
> cfq-iosched may not help you all that much in the end.

The main advantage I hope for is to reduce build and install time (it's
much quicker to rebuild a module, copy it into /lib/modules, perhaps
upgrade the initramfs, etc., than it is to rebuild an entire kernel, all
its modules, etc.).


Paul

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