From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755224AbXLKUTz (ORCPT ); Tue, 11 Dec 2007 15:19:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752772AbXLKUTs (ORCPT ); Tue, 11 Dec 2007 15:19:48 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:46714 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752657AbXLKUTr (ORCPT ); Tue, 11 Dec 2007 15:19:47 -0500 Date: Tue, 11 Dec 2007 21:19:30 +0100 From: Ingo Molnar To: Andi Kleen Cc: linux-kernel@vger.kernel.org Subject: Re: Performance overhead of get_cycles_sync Message-ID: <20071211201930.GB22397@elte.hu> References: <475E8C8B.7070308@qumranet.com> <20071211133738.GA8150@elte.hu> <475E9A92.4030001@qumranet.com> <20071211142717.GA15903@elte.hu> <20071211083513.56c2a385@laptopd505.fenrus.org> <20071211170334.GA30144@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Andi Kleen wrote: > Ingo Molnar writes: > > > the TSC clocksource (and hence the vsyscall code) is turned off on > > systems that fail the TOD/CLOCK portion of this test: > > Which is not on core2 which was the question about. And if it was > turned off it wouldn't use get_cycles_sync() at all. it is turned off on core2 too: # cat /sys/devices/system/clocksource/clocksource0/current_clocksource acpi_pm Ingo