From: Andrew Morton <akpm@osdl.org>
To: Anton Altaparmakov <aia21@cam.ac.uk>
Cc: axboe@suse.de, AChittenden@bluearc.com, davej@redhat.com,
linux-kernel@vger.kernel.org, lwoodman@redhat.com
Subject: Re: adding swap workarounds oom - was: Re: Out of Memory: Killed process 16498 (java).
Date: Fri, 3 Feb 2006 01:26:07 -0800 [thread overview]
Message-ID: <20060203012607.0a9d6730.akpm@osdl.org> (raw)
In-Reply-To: <1138958409.3828.9.camel@imp.csi.cam.ac.uk>
Anton Altaparmakov <aia21@cam.ac.uk> wrote:
>
> Hi,
>
> On Fri, 2006-01-27 at 14:39 +0000, Anton Altaparmakov wrote:
> > A colleague has a server (which does backups) that is incapable of doing
> > a backup due to the backup process being killed due to OOM after
> > anywhere between 30s and a few minutes of running... And the backup
> > process is just a simple program that does the equivalent of "dd with
> > one source but two destinations" where the source is an lvm/dm snapshot
> > and the two destinations are two different tape drives attached via
> > scsi. That is pretty critical, admittedly only to us and that system...
>
> We found a workaround for the OOM problems on above server yesterday.
>
> Add a 1MiB swap file:
>
> dd if=/dev/zero of=/var/swapfile bs=1024 count=1024
> mkswap /var/swapfile
> swapon /var/swapfile
>
> Run backup script and no problems!
>
> Note: This is a suse SLES9 system and the problem is not present on
> kernel kernel-smp-2.6.5-7.193.i586.rpm and all earlier kernels and it is
> present on kernel-smp-2.6.5-7.201.i586.rpm and all later kernels
> including the latest kernel (2.6.5-7.244).
>
> Seems like a definite VM bug... Interestingly on the .244 kernel the
> OOM conditions print out a lot of debug information to dmesg about the
> memory use in the system and AFAICS none of the memory is exhausted! So
> it seems the system goes OOM without it actually being OOM because it
> detects that "free swap == 0" or something along those lines...
It does sound like that. Does it still happen if there's 1MB of swap
online and it's all full?
> Or do we nowadays require swap to be present?
Shouldn't be the case.
> The machine has 6GiB RAM so swap was turned off on it. (In our
> experience if a machine with a lot of concurrent connections starts
> swapping the system goes down the drain (it becomes too slow) so swap is
> not something we want on servers with 40000+ users...)
1MB of swap isn't likely to cause a lot of swapping.
> If the above is not enough information to find/fix the problem please
> let me know what more you would like to know...
It'd be nice to see the oom-killer output.
I don't recall a problem like this. I wonder if there are any suse changes
which might have triggered it.
next prev parent reply other threads:[~2006-02-03 9:26 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-27 11:53 Out of Memory: Killed process 16498 (java) Andy Chittenden
2006-01-27 14:21 ` Jens Axboe
2006-01-27 14:39 ` Anton Altaparmakov
2006-02-03 9:20 ` adding swap workarounds oom - was: " Anton Altaparmakov
2006-02-03 9:26 ` Andrew Morton [this message]
2006-02-03 11:01 ` Anton Altaparmakov
2006-02-03 13:54 ` Jens Axboe
2006-02-03 13:56 Andy Chittenden
2006-02-03 14:00 ` Jens Axboe
2006-02-22 10:43 Andy Chittenden
2006-02-22 13:34 ` Jens Axboe
2006-02-22 13:35 ` Jens Axboe
2006-02-22 13:38 ` Jens Axboe
2006-02-24 9:33 Andy Chittenden
[not found] <89E85E0168AD994693B574C80EDB9C270393BF0E@uk-email.terastack.bluearc.com>
2006-02-27 14:28 ` Jens Axboe
2006-02-27 14:50 Andy Chittenden
2006-02-27 14:56 ` Jens Axboe
2006-02-27 16:39 Andy Chittenden
2006-02-28 10:10 Andy Chittenden
2006-02-28 10:20 ` Jens Axboe
2006-02-28 10:27 Andy Chittenden
2006-02-28 10:29 ` Jens Axboe
2006-03-01 9:42 Andy Chittenden
2006-03-01 9:55 ` Jens Axboe
2006-03-01 10:47 Andy Chittenden
2006-03-01 12:15 ` Jens Axboe
2006-03-01 12:19 ` Jens Axboe
2006-03-01 12:23 ` Andi Kleen
2006-03-01 12:25 ` Jens Axboe
2006-03-01 13:34 Andy Chittenden
2006-03-01 13:41 ` Jens Axboe
2006-03-01 14:05 ` Andi Kleen
2006-03-01 14:18 ` Jens Axboe
2006-03-01 14:26 ` Andi Kleen
2006-03-01 14:34 ` Jens Axboe
2006-03-01 14:41 ` Andi Kleen
2006-03-01 15:00 ` Jens Axboe
2006-03-01 14:40 Andy Chittenden
[not found] <89E85E0168AD994693B574C80EDB9C270393C141@uk-email.terastack.bluearc.com>
2006-03-01 15:57 ` Jens Axboe
2006-03-02 10:46 Andy Chittenden
2006-03-02 11:10 ` Jens Axboe
2006-03-02 12:21 ` Andi Kleen
2006-03-02 12:26 ` Jens Axboe
2006-03-03 9:16 Andy Chittenden
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