nerijus at USERS.SOURCEFORGE.NET
Mon Nov 25 21:06:58 GMT 2002
On Mon, 25 Nov 2002 19:10:33 +0000 Julian Field <mailscanner at ECS.SOTON.AC.UK> wrote:
> By putting the directories into a ramdisk, you are forcing the OS to use a
> fixed amount of ram for this. In general, it is better to leave the OS to
> manage system resources itself, as it's usually better at it than the
> "fixed" value you give by having it in a ram disk.
Linux 2.4 has tmpfs filesystem, which does not have ramdisk problems. For
example, User-mode Linux can place virtual memory files in tmpfs:
Instead, we can use 'tmpfs' which is a dynamic RAM based file system.
tmpfs only uses the memory it needs, so unlike ramfs, we don't have to
set aside a whole chunk of RAM from the word go. Of course, as with any
other memory allocated on a system, if it's unused it will be swapped
out to disk. Assuming the host has plenty of memory, from a combination
of real RAM and swap space, we can create a large /tmp file system using
tmpfs, which is used by the UML kernels. On a host with 1Gb of RAM, we
can quite happily create a 4Gb /tmp file system, as long as it has enough
swap space to swap out the extra 3Gb of memory.
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