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From: Avi Kivity <avi@argo.co.il>
To: Oliver Neukum <neukum@fachschaft.cup.uni-muenchen.de>
Cc: Jeff Garzik <jgarzik@pobox.com>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	Jens Axboe <axboe@suse.de>
Subject: Re: userspace block driver?
Date: Wed, 09 Nov 2005 10:37:02 +0200	[thread overview]
Message-ID: <4371B52E.4030004@argo.co.il> (raw)
In-Reply-To: <Pine.LNX.4.58.0511090852440.22793@fachschaft.cup.uni-muenchen.de>

Oliver Neukum wrote:

>On Wed, 9 Nov 2005, Jeff Garzik wrote:
>
>  
>
>>Has anybody put any thought towards how a userspace block driver would work?
>>
>>Consider a block device implemented via an SSL network connection.  I don't
>>want to put SSL in the kernel, which means the only other alternative is to
>>pass data to/from a userspace daemon.
>>    
>>
>
>I am afraid this is impossible without some heavy infrastructure work.
>You will almost inevitably deadlock. Yes, you can mlock() your driver, but 
>that still will not tell the kernel that GFP_KERNEL must be replaced with 
>GFP_NOIO if it is triggered by syscalls you are doing.
>
>  
>
A simple patch can help here (in addition to mlockall()):

  http://www.ussg.iu.edu/hypermail/linux/kernel/0407.3/0297.html

you might want to increase the free memory target as well.

  reply	other threads:[~2005-11-09  8:37 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-11-09  7:27 userspace block driver? Jeff Garzik
2005-11-09  7:37 ` Neil Brown
2005-11-09  7:46   ` Jeff Garzik
2005-11-09  7:54     ` Jens Axboe
2005-11-09  8:01       ` Jeff Garzik
2005-11-09 12:42         ` Paulo Marques
2005-11-09 12:54           ` Miklos Szeredi
2005-11-09 14:04             ` Miklos Szeredi
2005-11-11  0:12               ` Andrew Morton
2005-11-11  5:59                 ` Miklos Szeredi
2005-11-09 10:12       ` Lars Marowsky-Bree
2005-11-09  7:50 ` Chris Wright
2005-11-09  7:55 ` Oliver Neukum
2005-11-09  8:37   ` Avi Kivity [this message]
2005-11-09 13:32 ` Jonathan Corbet
2005-11-09 20:56 ` Guennadi Liakhovetski
2005-11-12 23:42   ` Guennadi Liakhovetski
2005-11-10 13:13 ` Pavel Machek
2005-11-16  3:13 ` Michael Clark

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