/proc/sys/vm/freepages read-only?!?

David L. Parsley (parsley@linuxjedi.org)
Mon, 26 Mar 2001 10:44:19 -0500


Hi,

I'm trying to do some vm tuning for diskless (and therefore swapless)
devices. (I'm working on a distro that tftp's packages and runs
entirely in RAM)

Even on an X terminal with 64MB RAM, badly behaved apps can use lots of
ram in the Xserver, and what I'm seeing is a hang. The box is usually
still pingable, just unresponsive. I'm using cramfs pretty heavily, and
I think what's occuring is that the terminal gets too low on freepages,
and since pages used by X can't be swapped out, the box starts thrashing
the vm and is unable to get pages to uncompress into.

My first thought was echo (bigger numbers) > /proc/sys/vm/freepages -
but lo! - it's not writable anymore. I found comments in page_alloc.c
indicating it had to be read-only, but it seems it's only a safety
precaution. Something along the lines of values too small being 'bad
bad'.

help?
David

-- 
David L. Parsley
Network Administrator
Roanoke College
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