On Fri, Jun 14, 2013 at 01:58:52AM +0200, Alexander Graf wrote: > > Yeah, sounds like this really is the problem. So what I was asking you back > then was to take a look at the dynamic page reshuffling mechanisms that got > introduced with CMA and transparent huge pages. > > I don't think that preallocating yet another potentially fragmented pool of > bigger memory chunks - which your patch did - is the answer to this problem. > We just need to defragment normal system memory and delay HPT creation until > it's ready. It can't be that hard. > > Andrea, do you happen to have any hints for us here? We need roughly 16MB of > linear memory available when we create a virtual machine on POWER. Can we > somehow tell the mm system to shuffle such a big chunk free for us?
I have a guy in India (Aneesh Kumar K.V, same guy that did the THP patches) looking at using the CMA stuff. With CMA we can reserve a fairly large pool (say 5% or even 10% of system memory) without concern, since the memory is still usable for user processes, and that should help any fragmentation issues. If fragmentation still turns out to be a problem we can look at moving the HPTs around. Paul. -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
