Re: oom kill oddness.
From: Dave Jones
Date: Thu Sep 28 2006 - 20:22:58 EST
On Thu, Sep 28, 2006 at 05:17:06PM -0700, Andrew Morton wrote:
> On Fri, 29 Sep 2006 01:03:16 +0200 (CEST)
> Roman Zippel <zippel@xxxxxxxxxxxxxx> wrote:
> > Hi,
> > On Wed, 27 Sep 2006, Dave Jones wrote:
> > > 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 ?
> > I think I see the same thing on the other end on slow machines, here it
> > only takes a single compile job, which doesn't quite fit into memory and
> > another task (like top) which occasionally wakes up and tries to allocate
> > memory and then kills the compile job - that's very annoying.
> > AFAICT the basic problem is that "did_some_progress" in __alloc_pages() is
> > rather local information, other processes can still make progress and keep
> > this process from making progress, which gets grumpy and starts killing.
> > What's happing here is that most memory is either mapped or in the swap
> > cache, so we have a race between processes trying to free memory from the
> > cache and processes mapping memory back into their address space.
> Kernel versions please, guys. There have been a lot of oom-killer changes
Sorry, I've been stuck on 2.6.18 as that's what we're shipping in FC6 soon.
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