* Chris Webb <chris@xxxxxxxxxxxx> [2010-08-19 10:25:36]: > Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx> writes: > > > Can you give an idea of what the meminfo inside the guest looks like. > > Sorry for the slow reply here. Unfortunately not, as these guests are run on > behalf of customers. They install them with operating systems of their > choice, and run them on our service. > Thanks for clarifying. > > Have you looked at > > http://kerneltrap.org/mailarchive/linux-kernel/2010/6/8/4580772 > > Yes, I've been watching this discussions with interest. Our application is > one where we have little to no control over what goes on inside the guests, > but these sorts of things definitely make sense where the two are under the > same administrative control. > Not necessarily, in some cases you can use a guest that uses lesser page cache, but that might not matter in your case at the moment. > > Do we have reason to believe the problem can be solved entirely in the > > host? > > It's not clear to me why this should be difficult, given that the total size > of vm allocated to guests (and system processes) is always strictly less > than the total amount of RAM available in the host. I do understand that it > won't allow for as impressive overcommit (except by ksm) or be as efficient, > because file-backed guest pages won't get evicted by pressure in the host as > they are indistinguishable from anonymous pages. > > After all, a solution that isn't ideal, but does work, is to turn off swap > completely! This is what we've been doing to date. The only problem with > this is that we can't dip into swap in an emergency if there's no swap there > at all. If you are not overcommitting it should work, in my experiments I've seen a lot of memory used by the host as page cache on behalf of the guest. I've done my experiments using cgroups to identify accurate usage. -- Three Cheers, Balbir -- 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>