From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [PATCH QEMU-KVM 6/7] test: Add ipi_halt benchmark Date: Mon, 21 Sep 2009 22:54:11 -0300 Message-ID: <20090922015411.GA1967@amt.cnet> References: <1253523338-22784-1-git-send-email-avi@redhat.com> <1253523338-22784-7-git-send-email-avi@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mx1.redhat.com ([209.132.183.28]:18301 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751152AbZIVByW (ORCPT ); Mon, 21 Sep 2009 21:54:22 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id n8M1sQCD004047 for ; Mon, 21 Sep 2009 21:54:26 -0400 Content-Disposition: inline In-Reply-To: <1253523338-22784-7-git-send-email-avi@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Mon, Sep 21, 2009 at 11:55:37AM +0300, Avi Kivity wrote: > Wait for 2000 cycles after the IPI to allow the host to schedule out. > Measures wake-from-idle overhead. > > Signed-off-by: Avi Kivity > --- > kvm/user/test/x86/vmexit.c | 11 +++++++++++ > 1 files changed, 11 insertions(+), 0 deletions(-) > > diff --git a/kvm/user/test/x86/vmexit.c b/kvm/user/test/x86/vmexit.c > index 29bb32a..5088dc9 100644 > --- a/kvm/user/test/x86/vmexit.c > +++ b/kvm/user/test/x86/vmexit.c > @@ -66,6 +66,16 @@ static void ipi(void) > on_cpu(1, nop, 0); > } > > +static void ipi_halt(void) > +{ > + unsigned long long t; > + > + on_cpu(1, nop, 0); > + t = rdtsc() + 2000; > + while (rdtsc() < t) > + ; I don't get the 2000 cycle thing. Since vcpu1 is on hlt by default, just IPI'ing it to do nop() already includes wake-from-idle overhead? Other than this the remaining is very nice, please apply. > +} > + > static struct test { > void (*func)(void); > const char *name; > @@ -76,6 +86,7 @@ static struct test { > { mov_from_cr8, "mov_from_cr8" }, > { mov_to_cr8, "mov_to_cr8" }, > { ipi, "ipi", is_smp }, > + { ipi_halt, "ipi+halt", is_smp }, > }; > > static void do_test(struct test *test) > -- > 1.6.4.1