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, 1 May 2001 07:19:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 1 May 2001 07:19:16 -0400 Received: from cisco7500-mainGW.gts.cz ([194.213.32.131]:4100 "EHLO bug.ucw.cz") by vger.kernel.org with ESMTP id ; Tue, 1 May 2001 07:19:05 -0400 Message-ID: <20010430104231.C3294@bug.ucw.cz> Date: Mon, 30 Apr 2001 10:42:31 +0200 From: Pavel Machek To: "H. Peter Anvin" , linux-kernel@vger.kernel.org Subject: Re: X15 alpha release: as fast as TUX but in user space (fwd) In-Reply-To: <20010428215301.A1052@gruyere.muc.suse.de> <200104282256.f3SMuRW15999@vindaloo.ras.ucalgary.ca> <9cg7t7$gbt$1@cesium.transmeta.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.93i In-Reply-To: <9cg7t7$gbt$1@cesium.transmeta.com>; from H. Peter Anvin on Sat, Apr 28, 2001 at 10:13:11PM -0700 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > > In x86-64 there are special vsyscalls btw to solve this problem that export > > > a lockless kernel gettimeofday() > > > > Whatever happened to that hack that was discussed a year or two ago? > > The one where (also on IA32) a magic page was set up by the kernel > > containing code for fast system calls, and the kernel would write > > calibation information to that magic page. The code written there > > would use the TSC in conjunction with that calibration data. > > > > There was much discussion about this idea, even Linus was keen on > > it. But IIRC, nothing ever happened. > > > > We discussed this at the Summit, not a year or two ago. x86-64 has > it, and it wouldn't be too bad to do in i386... just noone did. Just wait what kind of problems it is able to bring on i386. Pavel PS: Hmm, how do you do timewarp for just one userland appliation with this installed? -- I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care." Panos Katsaloulis describing me w.r.t. patents at discuss@linmodems.org