[ILUG] Out of Memory
paul.jakma at compaq.com
Tue Mar 7 13:55:08 GMT 2000
On Tue, 7 Mar 2000, John P. Looney wrote:
> There is also that Linux locks up, completely, while Solaris/FreeBSD
> don't. And if they are cleverer at hosing userspace, doesn't that make
> them better at avoiding userspace ?
well, i suppose i could claim on a technicality that linux hasn't locked
up completely. It's just deadlocked, if there was some way to free
memory it would continue. But then i guess i'd be evading your main
> But it is. That's why they are fixing it!
it's not the VM they are fixing. It's the process killing stuff they're
fixing. Plus the ENOMEM thing. (but Stephen Tweedie reckons not
returning ENOMEM on OOM might actually be a good thing.. so maybe that's
not a bug).
> The tmpfs is a bit dogdy. You are using swap as /tmp. Writing into it,
> and filling it up should make the machine run out of RAM. However, most of
> the cases that I've seen that happen, the machine is still usable to some
> degree (at least enough to be able to telnet in & wipe it).
true. Like i said already, to sol's credit, the admin had no problem
telneting in, and he cleared tempfs and i could continue working
straight away. That was nice.
> But you can't. What about a rogue process that could be buggy, that a
> developer could be working on, and it goes nuts. It happened me loads of
> times about a year ago.
did you have limits set?
i've had exactly one hang on linux because of OOM. On a box that's used
as nfs/mail/dial-up server + X desktop/apps via XDM/telnet. I had
reinstalled RH, and forgot to add pam_limits.so to the pam.d/kdm file
(on my old RH setup i had pam.d/gdm pam.d/kdm linked to pam.d/xdm)..
only time it's ever happened to me. How can linux behave correctly for
me, incorrectly for you if linux is so broken?
> 2.2.x is a lot better than 2.0.x, but can still be hard-hung.
true. but by the same measure you can prevent OOM with limits...
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