On Tue, 16 Nov 2010 16:45:29 +0100 Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote: > > > Except that the per-task steal time gives you lot less detail, being > > > able to profile on vcpu exit/enter gives you a much more powerfull > > > performance tool. Aside from being able to measure the steal-time it > > > allows you to instantly find hypercalls (both explicit as well as > > > implicit), so you can also measure the hypercall induced steal-time as > > > well. > > > > Yes and no. The tracepoint idea looks interesting in itself. But that does > > not completely replace the per-task steal time. The hypervisor can take > > away the cpu anytime, it is still interesting to know which task was hit > > hardest by that. You could view the cpu time lost by a hypercall as > > "synchronous" steal time for the task, the remaining delta to the total > > per-task steal time as "asynchronous" steal time. > > Right, so there is no way the guest knows about the vcpu getting > scheduled, it can only derive the fact from hardware clocks after the > fact? Correct. -- blue skies, Martin. "Reality continues to ruin my life." - Calvin. -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
