From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [PATCH 6/6] don't compute pvclock adjustments if we trust the tsc Date: Tue, 27 Apr 2010 10:40:13 -0300 Message-ID: <20100427134013.GE18410@amt.cnet> References: <1272303988-21929-1-git-send-email-glommer@redhat.com> <1272303988-21929-2-git-send-email-glommer@redhat.com> <1272303988-21929-3-git-send-email-glommer@redhat.com> <1272303988-21929-4-git-send-email-glommer@redhat.com> <1272303988-21929-5-git-send-email-glommer@redhat.com> <1272303988-21929-6-git-send-email-glommer@redhat.com> <1272303988-21929-7-git-send-email-glommer@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, avi@redhat.com To: Glauber Costa Return-path: Received: from mx1.redhat.com ([209.132.183.28]:54534 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755893Ab0D0Nlq (ORCPT ); Tue, 27 Apr 2010 09:41:46 -0400 Content-Disposition: inline In-Reply-To: <1272303988-21929-7-git-send-email-glommer@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Mon, Apr 26, 2010 at 01:46:28PM -0400, Glauber Costa wrote: > If the HV told us we can fully trust the TSC, skip any > correction > > Signed-off-by: Glauber Costa > --- > arch/x86/include/asm/kvm_para.h | 5 +++++ > arch/x86/include/asm/pvclock-abi.h | 1 + > arch/x86/kernel/kvmclock.c | 3 +++ > arch/x86/kernel/pvclock.c | 4 ++++ > 4 files changed, 13 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h > index f019f8c..615ebb1 100644 > --- a/arch/x86/include/asm/kvm_para.h > +++ b/arch/x86/include/asm/kvm_para.h > @@ -21,6 +21,11 @@ > */ > #define KVM_FEATURE_CLOCKSOURCE2 3 > > +/* The last 8 bits are used to indicate how to interpret the flags field > + * in pvclock structure. If no bits are set, all flags are ignored. > + */ > +#define KVM_FEATURE_CLOCKSOURCE_STABLE_TSC 0xf8 > + > #define MSR_KVM_WALL_CLOCK 0x11 > #define MSR_KVM_SYSTEM_TIME 0x12 Please drop this. Its not certain what is the best method to reduce contention on the global variable. Whatever it is, can be done later.