Hi Ingo, Thomas, In the latest kernel (2.6.24-rc3) I noticed a drastic performance decrease for KVM networking. The reason is many vmexit (exit reason is cpuid instruction) caused by calls to gettimeofday that uses tsc sourceclock. read_tsc calls get_cycles_sync which might call cpuid in order to serialize the cpu.
Can you explain why the cpu needs to be serialized for every gettime call? Do we need to be that accurate? (It will also slightly improve physical hosts). I believe you have a reason and the answer is yes. In that case can you replace the serializing instruction with an instruction that does not trigger vmexit? Maybe use 'ltr' for example? Regards, Dor. ------------------------------------------------------------------------- SF.Net email is sponsored by: Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://sourceforge.net/services/buy/index.php _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
