Re: [PATCH] Prevent OOM from killing init

[Stephen Clouse <stephenc@theiqgroup.com>]

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On Sat, Mar 23, 2002 at 01:33:50AM +0100, Martin Dalecki wrote:
> AMEN! TO THIS!
> Uptime of a process is a much better mesaure for a killing candidate
> then it's size.

Thing is, if you take a good study of mm/oom_kill.c, it *does* take start time
into account, as well as CPU time.  The problem is that a process (like Oracle,
in our case) using ludicrous amounts of memory can still rank at the top of the 
list, even with the time-based reduction factors, because total VM is the
starting number in the equation for determining what to kill.  Oracle or what
not sitting at 80 MB for a day or two will still find a way to outrank the
newly-started 1 MB shell process whose malloc triggered oom_kill in the first
place.

If anything, time really needs to be a hard criterion for sorting the final list
on and not merely a variable in the equation and thus tied to vmsize.

This is why the production database boxen aren't running 2.4 yet.  I can control
Oracle's usage very finely (since it uses a fixed memory pool preallocated at
startup), but if something else decides to fire up on there (like the nightly
backup and maintenance routine) and decides it needs just a pinch more memory
than what's available -- ick.  2.2.x doesn't appear to enforce new memory 
allocation with a sniper rifle -- the new process just suffers a pleasant ("Out
of memory!") or violent (SIGSEGV) death.

- -- 
Stephen Clouse <stephenc@theiqgroup.com>
Senior Programmer, IQ Coordinator Project Lead
The IQ Group, Inc. <http://www.theiqgroup.com/>

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