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From: Jens Axboe <jaxboe@fusionio.com>
To: Paul Bolle <pebolle@tiscali.nl>
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>
Subject: Re: Mysterious CFQ crash and RCU
Date: Wed, 25 May 2011 11:30:52 +0200	[thread overview]
Message-ID: <4DDCCC4C.5030606@fusionio.com> (raw)
In-Reply-To: <1306314848.9059.17.camel@t41.thuisdomein>

On 2011-05-25 11:13, Paul Bolle wrote:
> On Wed, 2011-05-25 at 10:46 +0200, Jens Axboe wrote:
>> Are you easily able to test a patch out?
> 
> Yes. 

Super!

>> Having a
>> test case on your machine that is as easily reproducible as it seems to
>> be, would be a great place to test ideas out.
> 
> Maybe I should now also try to build CFQ (and the other schedulers, I
> guess) as a module (instead of Fedora's default of builtin). That might
> make it both easier and quicker to iterate over a number of ideas.

As most debug patches will likely end up in cfq, yes that makes sense.

> Does using the schedulers as modules require any handholding (on your
> part, I'm afraid) or is it not really different from using any other
> kernel module?

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.


-- 
Jens Axboe


  reply	other threads:[~2011-05-25  9:30 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-19 22:24 Mysterious CFQ crash and RCU Vivek Goyal
2011-05-21 21:00 ` Paul E. McKenney
2011-05-21 22:23   ` Paul Bolle
2011-05-21 23:54     ` Paul E. McKenney
2011-05-22 19:30       ` Paul Bolle
2011-05-22 20:13         ` Paul E. McKenney
2011-05-23 15:21   ` Vivek Goyal
2011-05-23 15:38     ` Paul E. McKenney
2011-05-23 22:20       ` Paul Bolle
2011-05-24  4:14         ` Paul E. McKenney
2011-05-24  9:41         ` Jens Axboe
2011-05-24 14:35           ` Paul E. McKenney
2011-05-24 14:51             ` Jens Axboe
2011-05-24 15:42               ` Paul E. McKenney
2011-05-24 15:51                 ` Paul E. McKenney
2011-05-25  8:28           ` Paul Bolle
2011-05-25  8:46             ` Jens Axboe
2011-05-25  9:13               ` Paul Bolle
2011-05-25  9:30                 ` Jens Axboe [this message]
2011-05-25  9:40                   ` Paul Bolle
2011-05-25 12:48               ` Paul Bolle
2011-05-25 12:51                 ` Jens Axboe
2011-05-25 17:28               ` Paul Bolle
2011-05-25 18:59                 ` Jens Axboe
2011-05-25 10:17       ` Paul Bolle
2011-05-25 15:33         ` Paul E. McKenney
2011-05-25 17:44           ` Paul Bolle
2011-05-25 20:40             ` Paul E. McKenney
2011-05-26  9:15       ` Paul Bolle
2011-06-03  5:07         ` Paul E. McKenney
2011-06-03 13:45           ` Vivek Goyal
2011-06-03 15:33             ` Paul E. McKenney
2011-06-03 16:54               ` Paul E. McKenney
2011-06-04 12:22             ` Paul Bolle
2011-06-04 12:50           ` Paul Bolle
2011-06-04 16:03             ` Paul E. McKenney
2011-06-04 22:48               ` Paul Bolle
2011-06-04 23:06                 ` Paul E. McKenney
2011-08-04 15:05                   ` Vivek Goyal
2011-08-04 19:43                     ` Jens Axboe
2011-08-04 19:51                       ` Vivek Goyal
2011-06-05  6:56                 ` Jens Axboe
2011-06-05  8:39                   ` Paul Bolle
2011-06-05 10:38                   ` Paul Bolle
2011-06-05 22:51                     ` Jens Axboe
2011-06-06 14:28                   ` Vivek Goyal
2011-05-23 15:36   ` Vivek Goyal

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