From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 17 Dec 2002 15:04:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 17 Dec 2002 15:04:37 -0500 Received: from neon-gw-l3.transmeta.com ([63.209.4.196]:58121 "EHLO neon-gw.transmeta.com") by vger.kernel.org with ESMTP id ; Tue, 17 Dec 2002 15:04:34 -0500 Message-ID: <3DFF8520.7030600@transmeta.com> Date: Tue, 17 Dec 2002 12:12:16 -0800 From: "H. Peter Anvin" Organization: Transmeta Corporation User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.3a) Gecko/20021119 X-Accept-Language: en, sv MIME-Version: 1.0 To: Alan Cox CC: Linus Torvalds , Dave Jones , Ingo Molnar , Linux Kernel Mailing List Subject: Re: Intel P6 vs P7 system call performance References: <3DFF772E.2050107@transmeta.com> <1040158171.20765.23.camel@irongate.swansea.linux.org.uk> In-Reply-To: <1040158171.20765.23.camel@irongate.swansea.linux.org.uk> 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 Alan Cox wrote: > On Tue, 2002-12-17 at 19:12, H. Peter Anvin wrote: > >>The complexity only applies to nonsynchronized TSCs though, I would >>assume. I believe x86-64 uses a vsyscall using the TSC when it can >>provide synchronized TSCs, and if it can't it puts a normal system call >>inside the vsyscall in question. > > > For x86-64 there is the hpet timer, which is a lot saner but I don't > think we can mmap it > It's only necessary, though, when TSC isn't usable. TSC is psycho fast when it's available. Just about anything is saner than the old 8042 or whatever it is called timer chip, though... -hpa