On Monday 08 September 2008 21:08:02 Liu Yu-B13201 wrote: > > > You can't assume that TLB1 does not contain user mappings, because > > that's not true with hugetlbfs. Of course, hugetlbfs doesn't (yet?) > > exist for e500, so the assumption is valid until that happens. > > > > However, we *really* need large host page mappings to make KVM fast. > > Right now we have to split guest large pages (covering the > > kernel) into > > lots of 4K mappings, which means our TLB miss rate is *much* > > higher than > > if we could use hugetlbfs on the host. In that case, we could use > > hugetlbfs large user pages to back the guest kernel mappings. > > > > Yes. It's a problem. But I afraid e500 would not use hugetlbfs, > as it means to give up 512-entry TLB0, while TLB1 has only 16 entries. I don't think you'd need to "give up" anything -- some parts of user memory would be backed with 4K pages, and some parts with large pages. -- Hollis Blanchard IBM Linux Technology Center -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
