Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753946Ab0DUAFx (ORCPT ); Tue, 20 Apr 2010 20:05:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:21683 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753853Ab0DUAFv (ORCPT ); Tue, 20 Apr 2010 20:05:51 -0400 Message-ID: <4BCE4153.4010801@redhat.com> Date: Tue, 20 Apr 2010 14:05:39 -1000 From: Zachary Amsden User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.8) Gecko/20100301 Fedora/3.0.3-1.fc12 Thunderbird/3.0.3 MIME-Version: 1.0 To: Avi Kivity CC: Peter Zijlstra , Glauber Costa , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Jeremy Fitzhardinge , Marcelo Tosatti Subject: Re: [PATCH 1/5] Add a global synchronization point for pvclock 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> <4BCC3520.6090305@redhat.com> <1271674273.1674.777.camel@laptop> <4BCC3654.2090600@redhat.com> <4BCCA281.6040509@redhat.com> <4BCD7643.4000102@redhat.com> In-Reply-To: <4BCD7643.4000102@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1609 Lines: 44 On 04/19/2010 11:39 PM, Avi Kivity wrote: > On 04/19/2010 09:35 PM, Zachary Amsden wrote: >>>>> Sockets and boards too? (IOW, how reliable is TSC_RELIABLE)? >>>> Not sure, IIRC we clear that when the TSC sync test fails, eg when we >>>> mark the tsc clocksource unusable. >>> >>> Worrying. By the time we detect this the guest may already have >>> gotten confused by clocks going backwards. >> >> >> Upstream, we are marking the TSC unstable preemptively when hardware >> which will eventually sync test is detected, so this should be fine. > > ENOPARSE? > Instead of detecting TSC warp, c1e_idle, power_saving_mwait_init, tsc_check_state, dmi_mark_tsc_unstable all do something similar to this to disable TSC before warp even occurs: static void c1e_idle(void) { if (need_resched()) return; if (!c1e_detected) { u32 lo, hi; rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi); if (lo & K8_INTP_C1E_ACTIVE_MASK) { c1e_detected = 1; if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) mark_tsc_unstable("TSC halt in AMD C1E"); printk(KERN_INFO "System has AMD C1E enabled\n"); set_cpu_cap(&boot_cpu_data, X86_FEATURE_AMDC1E); } } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/