Re: tmpfs

From: Horst von Brand (vonbrand@sleipnir.valparaiso.cl)
Date: Sat Feb 19 2000 - 20:30:09 EST


ADAM Sulmicki <adam@cfar.umd.edu> said:
> Solaris has something called tmpfs. Some ppl wanted it under
> linux.

Yep. Solaris needs this, as even the (very fast) tmpfs over RAM on Solaris
is slower than ext2 over HDD on Linux ;-)

> An easy way to do is create ramdisk and then just mount it
> as /tmp. It comes out especially handy if you boot whole
> system in readonly mode and some programs require writable
> tmp (like X for its pipes).

It is _not_ the same thing. tmpfs lives in virtual memory (RAM + swap), and
it uses up memory according to the space used. ramdisk lives in RAM, and
has a fixed size. It is handled just like any other block device. Besides,
if your data resides in RAM (or a mockup of same), you can use data
structures and algorithms that are out of the question on disk. Conversely,
creating a ramdisk and mke2fs'ing it is a dumb kludge. Convenient and easy,
and saves you a special filesystem. But dumb anyway.

-- 
Horst von Brand                             vonbrand@sleipnir.valparaiso.cl
Casilla 9G, Viņa del Mar, Chile                               +56 32 672616

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