On Mon, Nov 04, 2013 at 09:30:42PM +0200, Michael S. Tsirkin wrote: > 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. I answer it already. -- Gleb. -- 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
