RAM disk.
Tom Kessler
kessler at hacketorium.Eng.Sun.COM
Wed Oct 10 07:05:42 AEST 1990
In article <1850 at necisa.ho.necisa.oz> boyd at necisa.ho.necisa.oz (Boyd Roberts) writes:
>When I hear `ram disk' I reach for my revolver. Now, repeat after me...
> What is the buffer cache? -- A ram disk.
>Increase NBUF and throw tmpfs away.
Whoa, hold on there. There are some performance wins with tmpfs
(once you get it working right :-) ) that you can't get by just upping
NBUF (with the SunOS/System V R 4 memory management NBUF doesn't do what
it used to do anyway :-) ). Remember that when you create and delete
lots of shortlived files you've got to update their inodes (yes, I know
i-nodes are cached as well as blocks). With the UFS file system you
actually go to disk quite frequently (mostly for recover reasons).
If you've marked this files system as a tmpfs the kernel doesn't have
to worry about getting your stuff out to disk ever because presumably
you don't care if the files are still there after a reboot.
Maybe you could tweak the file system to "know this" but for whatever
I've found tmpfs to speed up compiles quite a bit.
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