On 06/16/2011 09:08 AM, Peter Zijlstra wrote: > On Thu, 2011-06-16 at 08:08 -0600, David Ahern wrote: >> Command: >> perf stat -e instructions openssl speed aes >> >> Guest: >> 135,522,189,056 instructions # 0.00 insns per cycle >> >> >> Host: >> 346,082,922,185 instructions # 0.00 insns per cycle > > How does: perf stat -e instructions:u openssl speed aes, compare? I think the problem is that perf stat in the guest introduces significant overhead. I ran perf-record in the host on the VM pid while running 'perf stat openssl speed aes' in the guest. perf-report on that data shows: 18.06% 9226 [k] arch_local_irq_enable | |--99.77%-- kvm_arch_vcpu_ioctl_run | kvm_vcpu_ioctl | do_vfs_ioctl | sys_ioctl | system_call_fastpath | __GI___ioctl | 0x10100000002 --0.23%-- [...] and then perf-annotate on kvm_arch_vcpu_ioctl_run shows : vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); 21.47 : 1613a: 48 8b 3b mov (%rbx),%rdi David -- 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