Avi Kivity wrote: > Anthony Liguori wrote: >> Avi Kivity wrote: >>> Anthony Liguori wrote: >>> >>>> Implemented a hypercall queue that can be used when paravirt_ops >>>> lazy mode >>>> is enabled. This patch enables queueing of MMU write operations >>>> and CR >>>> updates. This results in about a 50% bump in kernbench performance. >>>> >>> >>> Nice! But 50%? a kernel build is at native-25%, so we're now 25% >>> faster than native? >> >> Well, I haven't measured KVM to be 25% of native with kernbench :-) >> On my LS21 (AMD), I get: > > I did, but using kbuild (a simple 'make' with defconfig), not > kernbench. I get (elapsed time) 308 sec for kvm and 243 sec for native.
kernbench is a little different. It does a find over the kernel source tree to attempt to get as much of the kernel in the page cache as possible. It also uses -j4 by default. > Intel however is much faster than AMD due to the recent optimizations, > and I guess we get some pagetable thrashing with kernbench vs. kbuild. > >> >> KVM >> Elapsed Time 1054.39 (25.8237) >> User Time 371.844 (8.57204) >> System Time 682.61 (17.7778) >> Percent CPU 99.8 (0.447214) Sleeps 50115 (475.693) >> >> KVM PV >> Elapsed Time 595.85 (13.7058) >> User Time 360.99 (9.56093) >> System Time 234.704 (4.21283) >> Percent CPU 99 (0) >> Context Switches 46989.8 (328.277) >> Sleep 47882.8 (242.583) >> >> NATIVE >> Elapsed Time 328.602 (0.212415) >> User Time 304.364 (0.353171) >> System Time 23.99 (0.325192) >> Percent CPU 99 (0) >> Context Switches 39785.2 (159.796) >> Sleeps 46398.6 (311.466) >> >> With Intel, we're still only about 60% of native to start out with. >> The PV patches take us to about 72%. >> > > These numbers are pretty bad. I'd like to improve them, even without PV. I agree. Do you know what's missing at this point? There isn't a whole lot of state saving going on for the light weight exit paths for SVM. Regards, Anthony Liguori ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
