From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 1/5] Add a global synchronization point for pvclock Date: Mon, 19 Apr 2010 13:53:11 +0300 Message-ID: <4BCC3617.6050106@redhat.com> References: <1271356648-5108-1-git-send-email-glommer@redhat.com> <1271356648-5108-2-git-send-email-glommer@redhat.com> <4BCA026D.3070309@redhat.com> <1271673975.1674.763.camel@laptop> <1271674154.1674.771.camel@laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Glauber Costa , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Jeremy Fitzhardinge , Marcelo Tosatti , Zachary Amsden To: Peter Zijlstra Return-path: In-Reply-To: <1271674154.1674.771.camel@laptop> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 04/19/2010 01:49 PM, Peter Zijlstra wrote: > >> Right, so on x86 we have: >> >> X86_FEATURE_CONSTANT_TSC, which only states that TSC is frequency >> independent, not that it doesn't stop in C states and similar fun stuff. >> >> X86_FEATURE_TSC_RELIABLE, which IIRC should indicate the TSC is constant >> and synced between cores. >> > Fun, we also have: > > X86_FEATURE_NONSTOP_TSC, which states the thing doesn't stop in C > states. > All of them? I though tsc stops in some mwait deep REM sleep thing. So what do we need? test for both TSC_RELIABLE and NONSTOP_TSC? IMO TSC_RELIABLE should imply NONSTOP_TSC. -- error compiling committee.c: too many arguments to function