[fedora-virt] disabling ksm by default

[Justin M. Forbes]

On Tue, 2009-10-27 at 16:05 +0000, Daniel P. Berrange wrote:
> On Tue, Oct 27, 2009 at 03:55:16PM +0000, Mark McLoughlin wrote:
> > On Tue, 2009-10-27 at 10:46 -0500, Justin M. Forbes wrote:
> > > On Tue, 2009-10-27 at 17:31 +0200, Izik Eidus wrote:
> > > > On 10/27/2009 04:42 PM, Justin M. Forbes wrote:
> > For Fedora 13, it'll be off by default in the kernel and the recommended
> > way of switching it on is with 'chkconfig ksm on'
> > 
> > For Fedora 12, it's on by default in the kernel, 'chkconfig ksm on' just
> > changes max pages and the only way of disabling it is by manually
> > writing zero to /sys/kernel/mm/ksm/run
> > 
> > IMHO, if we are to change anything for Fedora 12, we should move closer
> > to Fedora 13 behaviour, not further away from it - i.e. make it off by
> > default in the kernel, but I'm fine with delaying that until post GA
> > 
> > We'll probably end up with this behaviour in F12 updates at some point
> > anyway when 2.6.32 is pulled in
> 
> Agreed, we should change our custom patches to match upstream, so its
> off by default.

We have done this twice now, initially ksm defaulted to off, and to
merge with what was to become 2.6.32 we ended up with the default on and
the current page limits.  Of course upstream has changed again.
Behavior doesn't change with the init script.  People really don't know
how to check if ksm is on or off without checking the documentation.  As
long as our documentation points to the initscript instead of modifying
sysfs we get the desired behavior.

Justin