Nikola Ciprich wrote: > Hi Anthony! > Anthony Liguori wrote: > >> I would think you should get about 70% of native with what you've done >> about. I've not seen instabilities with CONFIG_KVM_CLOCK myself. >> >> Setting up a hugetlbfs mount and using -mem-path may give you a bit of >> a bump too but I'd be surprised if it was more than 5% >> > I've tried it now, and starting kvm with -mem-path pointing to hugetlbfs > mounted dir immediately fails and I see following message in dmesg of host: > VM: killing process qemu-system-x86 > pointing to tmpfs mounted dir seems to work, I'll measure performance > gain... >
You won't see a gain with tmpfs. Make sure you reserve huge pages first. For a 1GB guest, you'll need something like: echo 540 > /proc/sys/vm/nr_hugepages When you create a VM, you need a bit more memory than 1GB for per-guest overhead. That's why I reserve 540 instead of 512. You can probably get away with 530 really. Check that it succeeded by cat'ing /proc/meminfo. >> The next biggest win you're going to see is using NPT (available in >> the recent AMD Barcelona/Phenom processors). NPT + hugetblfs should >> get you pretty close to native (I'd reckon 95-98%). >> > Yup, it seemed to me that kvm performes WAY better on my phenom based > home desktop! I'll check that later too > Definitely. A parallel compile is one of the best case scenarios for NPT so you should see the most dramatic improvement there. >> On the Intel side of things, you'll have to wait until the Nehalem >> which will support EPT (which is Intel's version of NPT). >> >> Can you be specific about your guest configurations? Are you using >> -smp 8? >> > yes, I'm using -smp 8 > It's not quite apples to apples then since you're sharing CPUs with the host. Typically, if I'm benchmarking an 8-way system with 2GB of RAM, I'll create a 4-way guest with 1GB of RAM and then to generate native numbers, reboot the host with maxcpus=4 mem=1G. Regards, Anthony Liguori >> Regards, >> >> Anthony Liguori >> > > > > > > ------------------------------------------------------------------------- > This SF.net email is sponsored by the 2008 JavaOne(SM) Conference > Register now and save $200. Hurry, offer ends at 11:59 p.m., > Monday, April 7! Use priority code J8TLD2. > http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone > _______________________________________________ > kvm-devel mailing list > kvm-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/kvm-devel > ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Register now and save $200. Hurry, offer ends at 11:59 p.m., Monday, April 7! Use priority code J8TLD2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
