RE: oom killer and its superior braindamage in 2.4

From: Mikael Starvik (mikael.starvik@axis.com)
Date: Mon Feb 24 2003 - 04:13:37 EST


Does everyone agree that killing a process is always the best approach
to resolve an OOM? If the OOM is caused by e.g. a growing tmpfs or
memory leaks in the kernel it won't help much to kill processes that
may respawn.

Would it be useful if it was possible to register another oom-handler?
Some architectures could then choose to e.g. reboot the system instead.

/Mikael

-----Original Message-----
From: linux-kernel-owner@vger.kernel.org
[mailto:linux-kernel-owner@vger.kernel.org]On Behalf Of Marc-Christian
Petersen
Sent: Saturday, February 22, 2003 8:35 PM
To: linux-kernel@vger.kernel.org
Subject: oom killer and its superior braindamage in 2.4

Hi all,

I just thought (ok it was yesterday) about stress testing my mysql db.
I used this:
- mystress.pl localhost mysql root test 600 300 60 "select * from user"

It worked like a charme. So I tried:
- mystress.pl localhost mysql root test 1800 900 60 "select * from user"

My machine has 512MB RAM and 512MB SWAP.

I expected that the 2nd run will OOM my machine but I did not expect this
silly behaviour.

The following log entry appeared only _once_ (there were ~700 mysqld running)

- Feb 21 10:03:22 codeman kernel: Out of Memory: Killed process 1463 (mysqld).

Instead of really killing either mysqld or mystress.pl the OOM killer decided
to kill apache (apache did nothing but had 5 threads sleeping)

- Feb 21 10:04:57 codeman kernel: Out of Memory: Killed process 2657 (apache).

The above log entry (apache) appeared for about 4 hours every some seconds
(same PID) until I thought about sysrq-b to get out of this braindead
behaviour. The machine was somewhat dead for me because I was not able to do
anything but sysrq. The system itself was _not_ dead, there was massive disk
i/o. This is 2.4.20 vanilla.

Is there any chance we can fix this up?

ciao, Marc

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