From: Christoph Rohland <cr@sap.com>
To: =?iso-8859-1?q?Ra=FAlN=FA=F1ez?= de Arenas Coronado 
	<raul@viadomus.com>
Cc: rml@tech9.net, linux-kernel@vger.kernel.org
Subject: Re: Is /dev/shm needed?
In-Reply-To: <E16FkV9-00010E-00@DervishD.viadomus.com>
Organisation: SAP LinuxLab
Date: 17 Dec 2001 09:19:01 +0100
In-Reply-To: <E16FkV9-00010E-00@DervishD.viadomus.com>
Message-ID: <m3heqqi7ii.fsf@linux.local>
Lines: 32
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Hi Ra?lN??ez,

On Mon, 17 Dec 2001, Ra?lN??ez de Arenas Coronado wrote:
>     Hello Robert :)
> 
>>It is not needed.  /dev/shm mounted with tmpfs is only needed for
>>POSIX shared memory, which is still fairly rare.
> 
>     That this means that I can mount more than one 'tmpfs' just like
> if it's a *real* filesystem? I wasn't sure, since it's implemented
> thru the page cache.

Yes, every single mount is an independant tree.

>>It is dynamic, so you don't need to specify a size.
> 
>     Yes, I knew, I meant the maximum size. I don't want half of the
> RAM occupied just by a programming mistake ;)))

What I like most about /tmp in tmpfs is the ability to resize on the
fly: I have a big swap partition and a reasonable limit for /tmp and
/var/tmp.

When one of these gets full I can either stop the affending job or
increase the limit: If there is swap left I can simply increase the
limit. If swap is full I add a swap file on a real filesystem and
increase the limit.

Greetings
		Christoph

P.S: Documentation/filesystems/tmpfs.txt is in the 2.4.17-rc patch.

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