Re: Is /dev/shm needed?

Christoph Rohland
2001-12-17T08:20:53Z

Hi RaúlNúñez,

On Mon, 17 Dec 2001, RaúlNúñez 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.