On Thu, Oct 31, 2013 at 02:21:46AM +0200, Michael S. Tsirkin wrote: > commit 8bf00a529967dafbbb210b377c38a15834d1e979: > " KVM: VMX: add support for switching of PERF_GLOBAL_CTRL " was > as far as I can tell supposed to bring about performance improvement > on hardware that supports it? > Instead it seems to make the typical case (not running guest > under perf) a bit slower than it used to be. > the cost of VMexit goes up by about 50 cycles > on sandy bridge where the optimization in question > actually is activated. > > Why that's not a large regression, it's a far cry from > actually helping performance. > > So are we better off not using this feature? > What kind of workload is improved by this change? Ping. Let's revert 8bf00a529967dafbbb210b377c38a15834d1e979? I see a small performance gain from reverting it ... -- MST -- 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
