Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 17 Sep 2002 16:59:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 17 Sep 2002 16:59:07 -0400 Received: from pizda.ninka.net ([216.101.162.242]:11395 "EHLO pizda.ninka.net") by vger.kernel.org with ESMTP id ; Tue, 17 Sep 2002 16:58:52 -0400 Date: Tue, 17 Sep 2002 13:54:51 -0700 (PDT) Message-Id: <20020917.135451.49037528.davem@redhat.com> To: ak@suse.de Cc: linux-kernel@vger.kernel.org, johnstul@us.ibm.com, anton.wilson@camotion.com Subject: Re: do_gettimeofday vs. rdtsc in the scheduler From: "David S. Miller" In-Reply-To: References: <1032294559.22815.180.camel@cog.suse.lists.linux.kernel> <20020917.133933.69057655.davem@redhat.com.suse.lists.linux.kernel> X-Mailer: Mew version 2.1 on Emacs 21.1 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 812 Lines: 18 From: Andi Kleen Date: 17 Sep 2002 23:00:38 +0200 Also reading HPET is somewhat more costly than reading TSCs because it goes to the southbridge, so there are cases where using TSC is probably better (e.g. I think for networking packet time stamping the TSC is just fine with all its limitations) The cpu gets a bus clock input, so the system tick should be processor local as much as TSC is. It's boggling that this is being messed up so much. I can't believe Sun got something incredibly right (Ultra-III has a system tick) :-) - 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/