From: Guy Harris (guy@Auspex.COM)
Date: Thu Jul 22 1993 - 15:37:22 CDT

> It is possible to declare a chunk of memory as a ramdisk which is then
>treated like a normal disk by SunOS.

It's possible to do so, with sufficient effort, but that's not what
"tmpfs" does:

        1) "tmpfs" isn't a file system that lives on a normal disk; it's
           a file system specifically written to have its "metadata"
           (data structures used to access files) in kernel memory, and
           its data pages in memory backed up by swap space;

        2) "tmpfs" does not "declare a chunk of memory" as anything; the
           metadata lives in whatever pages the kernel memory allocator
           happens to parcel out to it, and the regular file data lives
           in *pageable* kernel virtual memory - i.e., it is *NOT* wired
           down in memory, and *can* get pushed out of memory to swap

Now, "tmpfs" may give at least some of you everything you'd want out of
a RAM disk file system, but it's *not* a RAM disk file system and should
*not* be confused with a RAM disk file system.

If you want a RAM disk, you'd have to get a RAM disk driver....

This archive was generated by hypermail 2.1.2 : Fri Sep 28 2001 - 23:08:02 CDT