On Fri, 2012-09-14 at 16:55 +0300, Itamar Heim wrote:
On 09/14/2012 03:28 PM, John A. Sullivan III wrote: ...
Moreover, all instances in memory only take the space of one instance. Thus, we get deduplication and KSM almost for free.
oVirt (RHEV) runs KSM only when the host memory gets fuller but I seem to remember that guys were able to have high 1000's of % of memory overcommit ratios I have heard rumors of high CPU utilization with KSM but we have not experimented enough with it ourselves to know. Is that an issue?
ksm takes cpu, but servers today are loaded with cores, but memory is still the expensive part. today we configure ksm to kick in only when memory is ~80%, which is when you'd usually be willing to pay the price of one of your cores spending some time on ksm, then the memory congestion on the host / losing memory overcommit. That's where VServer is so great - we get the same results without the overhead. I assume oVirt does not change that part. Still, we are looking forward to exploring it as we really have no other option for Windows desktops and servers. Thanks - John