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From: Pavel Machek <pavel@ucw.cz>
To: Paul Clements <paul.clements@steeleye.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, nbd-general@lists.sourceforge.net,
	Laurent Vivier <Laurent.Vivier@bull.net>
Subject: Re: [PATCH 1/1] NBD: allow nbd to be used locally
Date: Tue, 11 Mar 2008 11:09:04 +0100	[thread overview]
Message-ID: <20080311100904.GA807@elf.ucw.cz> (raw)
In-Reply-To: <47D56F4A.5070208@steeleye.com>

On Mon 2008-03-10 13:26:34, Paul Clements wrote:
> Pavel Machek wrote:
>
>>> This patch allows a Network Block Device to be mounted locally 
>>> (nbd-client to nbd-server over 127.0.0.1).
>>>
>>> It creates a kthread to avoid the deadlock described in NBD tools 
>>> documentation. So, if nbd-client hangs waiting for pages, the kblockd 
>>> thread can continue its work and free pages.
>>
>> What happens if your new kthread blocks on memory allocation?
>
> Well, we expect that. The reason for the new thread is so that it hangs, 
> rather than kblockd hanging (which on a UP system brings all I/O to a 
> halt). As long as kblockd can continue making progress, we eventually free 
> up memory and then NBD can finish its requests, too.

...unless all the memory is in dirty buffers for nbd, and nbd server
is swapped out or something?
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

  reply	other threads:[~2008-03-11 13:10 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-03-09 22:47 Paul Clements
2008-03-10 10:29 ` Pavel Machek
2008-03-10 17:26   ` Paul Clements
2008-03-11 10:09     ` Pavel Machek [this message]
2008-03-24 20:37       ` [Nbd] " Wouter Verhelst
2008-03-24 21:58         ` Pavel Machek

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