On Fri, 2010-04-30 at 10:13 +0300, Avi Kivity wrote: > On 04/30/2010 04:45 AM, Dave Hansen wrote: > > > > A large portion of CMM2's gain came from the fact that you could take > > memory away from guests without _them_ doing any work. If the system is > > experiencing a load spike, you increase load even more by making the > > guests swap. If you can just take some of their memory away, you can > > smooth that spike out. CMM2 and frontswap do that. The guests > > explicitly give up page contents that the hypervisor does not have to > > first consult with the guest before discarding. > > > > Frontswap does not do this. Once a page has been frontswapped, the host > is committed to retaining it until the guest releases it. It's really > not very different from a synchronous swap device. > > I think cleancache allows the hypervisor to drop pages without the > guest's immediate knowledge, but I'm not sure. Gah. You're right. I'm reading the two threads and confusing the concepts. I'm a bit less mystified why the discussion is revolving around the swap device so much. :) -- Dave -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>