Re: ramdisk/tmpfs/ramfs/memfs ?

Christoph Rohland (cr@sap.com)
27 Apr 2001 17:38:19 +0200


Hi Padraig,

On Fri, 27 Apr 2001, Padraig Brady wrote:
> I don't have swap so don't need tmpfs, but could probably
> use it anyway without a backing store?

Yes, it does not need backing store.

> Anyway why was ramfs created if tmpfs existed, unless tmpfs requires
> backing store? They both seem to have been written around the same
> time?

- shm fs was written as a specialized fs to implement POSIX shared
memory based on SYSV shm.
- ramfs was introduced shortly after shm fs and was meant as a
programming example for a minimal virtual filesystem.
- Later shm fs was redone to use the same methods like ramfs but still
was only useable for shared memory.
- After the release of 2.4.0, I extended shm fs to support read/write
and thus be tmpfs and since then it can replace ramfs.

Greetings
Christoph

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