From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: [PATCH 1/5] Add a global synchronization point for pvclock Date: Fri, 23 Apr 2010 12:22:34 -0700 Message-ID: <4BD1F37A.6040801@goop.org> References: <1271675100.1674.818.camel@laptop> <4BCC3A3E.9070909@redhat.com> <20100419142158.GD14158@mothafucka.localdomain> <4BCC69D5.3050209@redhat.com> <1271688411.1488.248.camel@laptop> <4BCC8246.9040202@goop.org> <4BCD748E.7080007@redhat.com> <4BCDF12C.1020702@goop.org> <4BCDF85C.3000004@redhat.com> <4BCE0399.2010708@goop.org> <20100422131113.GA3364@mothafucka.localdomain> <4BD0FB92.4060301@redhat.com> <4BD169B5.4000409@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Zachary Amsden , Glauber Costa , Peter Zijlstra , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Marcelo Tosatti To: Avi Kivity Return-path: Received: from claw.goop.org ([74.207.240.146]:59329 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751494Ab0DWTWf (ORCPT ); Fri, 23 Apr 2010 15:22:35 -0400 In-Reply-To: <4BD169B5.4000409@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 04/23/2010 02:34 AM, Avi Kivity wrote: >> >> diff -rup a/time-warp-test.c b/time-warp-test.c >> --- a/time-warp-test.c 2010-04-15 16:30:13.955981607 -1000 >> +++ b/time-warp-test.c 2010-04-15 16:35:37.777982377 -1000 >> @@ -91,7 +91,7 @@ static inline unsigned long long __rdtsc >> { >> DECLARE_ARGS(val, low, high); >> >> - asm volatile("cpuid; rdtsc" : EAX_EDX_RET(val, low, high)); >> + asm volatile("cpuid; rdtsc" : EAX_EDX_RET(val, low, high) :: >> "ebx", "ecx"); >> >> > > > Plus, replace cpuid by lfence/mfence. cpuid will trap. I presume the clobbers are needed for cpuid; if you use [lm]fence then they shouldn't be needed, right? J