[fedora-virt] disabling ksm by default
Mark McLoughlin
markmc at redhat.com
Tue Oct 27 10:12:49 UTC 2009
Hi Izik,
On Tue, 2009-10-27 at 00:55 +0200, Izik Eidus wrote:
> Hi, I saw that Fedora 12 will have ksm tunning script that control the
> ksm speed / kernel pages allocation.
>
> The only problem that I have is - as far as I remember ksm is by default
> enabled and only with 2000 kernel pages...
> What I am worried about is that users wont use the ksm tunning script
> and would just run ksm with this 2000 kernel pages -
> the result would be that ksm will probably merge just the zero pages
> (that could be alot of memory) and the user might not know
> that much more memory can be saved...
>
> Is it possible to at least make ksm disabled by default? so the users
> will have to run the ksm tunning script when they want to start ksm?
ksm is disabled by default currently
> And if we set it to disabled by default, cant we set the initialized
> values into more realistic value? (like 1/4 of the memory in the
> mainline kernels? )
Here's the logic we have in the init script:
# unless KSM_MAX_KERNEL_PAGES is set, let ksm munch up to half of total memory.
default_max_kernel_pages () {
local total pagesize
total=`awk '/^MemTotal:/ {print $2}' /proc/meminfo`
pagesize=`getconf PAGESIZE`
echo $[total * 1024 / pagesize / 2]
}
git tree for the scripts here:
http://gitorious.org/ksm-control-scripts/ksm-control-scripts
Suggestions, comments, patches etc. welcome
Thanks,
Mark.
More information about the Fedora-virt
mailing list