Re: la la la la ... swappiness

[Andrew Morton <akpm@osdl.org>]

> On Sun, 3 Dec 2006 00:16:38 -0600 "Aucoin" <Aucoin@Houston.RR.com> wrote:
> I set swappiness to zero and it doesn't do what I want!
> 
> I have a system that runs as a Linux based data server 24x7 and occasionally
> I need to apply an update or patch. It's a BIIIG patch to the tune of
> several hundred megabytes, let's say 600MB for a good round number. The
> server software itself runs on very tight memory boundaries, I've
> preallocated a large chunk of memory that is shared amongst several
> processes as a form of application cache, there is barely 15% spare memory
> floating around.
> 
> The update is delivered to the server as a tar file. In order to minimize
> down time I untar this update and verify the contents landed correctly
> before switching over to the updated software.
> 
> The problem is when I attempt to untar the payload disk I/O starts caching,
> the inactive page count reels wildly out of control, the system starts
> swapping, OOM fires and there goes my 4 9's uptime. My system just suffered
> a catastrophic failure because I can't control pagecache due to disk I/O.

kernel version?

> I need a pagecache throttle, what do you suggest?

Don't set swappiness to zero...   Leaving it at the default should avoid
the oom-killer.