Nikola Ciprich wrote: > Hi, > I spent some time trying to tune performance of KVM guest using kernel > compilation as a kind of benchmark (I'm using virtual machines for > compiling a lot, so it's good benchmark for me in general) > > Host machine: 2x quad core XEON E5420 @ 2.50GHz, 4GB RAM, 2.6.24 + kvm-64 > guest configuration: all 8 cores available, 2GB RAM, 2.6.24 or latest GIT > + kvm-64 > > some results: > - compilation in KVM guest is roughly 2x slower than on bare metal. >
50% scaling is actually quite good for 8-way. What do you get for 4-way guests? > - enabling CONFIG_KVM_GUEST under latest GIT with kvm-64 patch applied > decreased compile time by about 10%, which is nice! > > We expect to improve this some more as paravirt_ops improves. > Is there currently anything more I could do to improve performance? I'm > wandering what is slowing compilation, if I compare some CPU intensive > application (ie bzip2), it seems to run in nearly native speed, but kernel > compilation is much slower even if run from ramdisk, maybe it could be > improved further by tunning scheduler etc? > > As others mentioned, large pages may help somewhat, as well as newer hardware. kvm-65 also improves scalability. How much cpu does the qemu process consume? Perfect utilization would be around 800%. What's the system/user ratio (I think you need to use 2.6.25-rc to get accurate results for this)? Can you provide the result of 'kvm_stat -1' taken a few times during a compile run? -- Any sufficiently difficult bug is indistinguishable from a feature. ------------------------------------------------------------------------- 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
