Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422771AbXBALgE (ORCPT ); Thu, 1 Feb 2007 06:36:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1422780AbXBALgE (ORCPT ); Thu, 1 Feb 2007 06:36:04 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:46703 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422771AbXBALgB (ORCPT ); Thu, 1 Feb 2007 06:36:01 -0500 Date: Thu, 1 Feb 2007 12:34:40 +0100 From: Ingo Molnar To: jbohac@suse.cz Cc: Andi Kleen , linux-kernel@vger.kernel.org, Vojtech Pavlik , arjan@infradead.org, tglx@linutronix.de, johnstul@us.ibm.com Subject: Re: [patch 0/9] x86_64: reliable TSC-based gettimeofday Message-ID: <20070201113440.GA26453@elte.hu> References: <20070201095952.589234000@jet.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070201095952.589234000@jet.suse.cz> User-Agent: Mutt/1.4.2.2i X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -3.7 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-3.7 required=5.9 tests=ALL_TRUSTED,BAYES_05 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts -0.4 BAYES_05 BODY: Bayesian spam probability is 1 to 5% [score: 0.0456] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2017 Lines: 47 * jbohac@suse.cz wrote: > This implementation allows the current time to be approximated by > reading the CPU's TSC even on SMP machines with unsynchronised TSCs. > This allows us to have a very fast gettimeofday() vsyscall on all SMP > machines supporting the RDTSCP instruction (AMD) or having > synchronised TSCs (Intel). > > Inter-CPU monotonicity can not, however, be guaranteed in a vsyscall, > so vsyscall is not used by default. Still, the syscall version of > gettimeofday is a lot faster using the TSC approximation instead of > other hardware timers. ok, this looks mostly good to me - but this definitely should be based /ontop/ of the x86_64 GTOD code. I.e. ontop of these patches in -mm: generic-vsyscall-gtod-support-for-generic_time.patch generic-vsyscall-gtod-support-for-generic_time-tidy.patch time-x86_64-hpet_address-cleanup.patch revert-x86_64-mm-ignore-long-smi-interrupts-in-clock-calibration.patch time-x86_64-split-x86_64-kernel-timec-up.patch time-x86_64-split-x86_64-kernel-timec-up-tidy.patch time-x86_64-split-x86_64-kernel-timec-up-fix.patch reapply-x86_64-mm-ignore-long-smi-interrupts-in-clock-calibration.patch time-x86_64-convert-x86_64-to-use-generic_time.patch time-x86_64-convert-x86_64-to-use-generic_time-fix.patch time-x86_64-convert-x86_64-to-use-generic_time-tidy.patch time-x86_64-hpet-fixup-clocksource-changes.patch time-x86_64-tsc-fixup-clocksource-changes.patch time-x86_64-re-enable-vsyscall-support-for-x86_64.patch time-x86_64-re-enable-vsyscall-support-for-x86_64-tidy.patch also, note that there is a new TSC synchronization check code in -mm as well: x86-rewrite-smp-tsc-sync-code.patch this should be ontop of that too. (and ontop of the high-res timers queue) Ingo - 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/