On Sun, Nov 9, 2014 at 8:33 PM, Wanpeng Li <wanpeng.li@xxxxxxxxxxxxxxx> wrote: > Hi Andy, > On Fri, Nov 07, 2014 at 06:25:18PM -0800, Andy Lutomirski wrote: >>At least on Sandy Bridge, letting the CPU switch IA32_EFER is much >>faster than switching it manually. >> >>I benchmarked this using the vmexit kvm-unit-test (single run, but >>GOAL multiplied by 5 to do more iterations): >> >>Test Before After Change >>cpuid 2000 1932 -3.40% >>vmcall 1914 1817 -5.07% >>mov_from_cr8 13 13 0.00% >>mov_to_cr8 19 19 0.00% >>inl_from_pmtimer 19164 10619 -44.59% >>inl_from_qemu 15662 10302 -34.22% > > What's the difference of IA32_EFER between guest and host in your config? > > IIUC, > - NX is not consistent > IA32_EFER will be auto load w/ and w/o the patch. > - SCE is not consistent > IA32_EFER will be switched through wrmsr(urn) w/o the patch, and auto load > w/ the patch. This is with kvm-unit-test as is, so NX is consistent but SCE is different. --Andy -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
