On Fri, Oct 30, 2009 at 10:00:28AM +0000, Richard W.M. Jones wrote:
On Tue, Oct 27, 2009 at 10:12:49AM +0000, Mark McLoughlin wrote:
> ksm is disabled by default currently
[...]
> # unless KSM_MAX_KERNEL_PAGES is set, let ksm munch up to half of total memory.
Mark, can you summarise why we wouldn't want KSM to be enabled by
default, and why we need to limit it to half of total memory?
The limit to half of total memory is because ksm pages are unswappable at
this time. To be fixed in a future kernel. As for enabling by default,
the more I think about it, the more this makes sense. The ksm initscript
is shipped with qemu, so anyone with it installed should be interested in
virt, and the value of max_kernel_pages doesn't matter if you are not
running anything which marks memory mergeable, which only kvm does at the
moment.
Justin