linux-kernel - Re: oom kill oddness.

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Date:	Fri, 29 Sep 2006 16:03:14 -0400
From:	Larry Woodman <lwoodman@...hat.com>
To:	linux-kernel@...r.kernel.org
Subject: Re: oom kill oddness.

>
>
>So I have two boxes that are very similar.
>Both have 2GB of RAM & 1GB of swap space.
>One has a 2.8GHz CPU, the other a 2.93GHz CPU, both dualcore.
>
>The slower box survives a 'make -j bzImage' of a 2.6.18 kernel tree
>without incident. (Although it takes ~4 minutes longer than a -j2)
>
>The faster box goes absolutely nuts, oomkilling everything in sight,
>until eventually after about 10 minutes, the box locks up dead,
>and won't even respond to pings.
>
>Oh, the only other difference - the slower box has 1 disk, whereas the
>faster box has two in RAID0.   I'm not surprised that stuff is getting
>oom-killed given the pathological scenario, but the fact that the
>box never recovered at all is a little odd.  Does md lack some means
>of dealing with low memory scenarios ?
>
>	Dave
>
Dave, this has been a problem since the out_of_memory() function was 
changed
between 2.6.10 and 2.6.11.  Before this change out_of_memory() required 
multiple
calls within 5 seconds before actually OOM killed a process.  After the 
change(in 2.6.11)
a single call to out_of_memory() results in OOM killing a process.  The 
following patch
allows the 2.6.18 system to run under much more memory pressure before 
it OOM kills.




View attachment "oomkill.patch" of type "text/plain" (2192 bytes)