From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 2 May 2001 14:18:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 2 May 2001 14:18:24 -0400 Received: from zmailer.org ([194.252.70.162]:32519 "EHLO zmailer.org") by vger.kernel.org with ESMTP id ; Wed, 2 May 2001 14:18:14 -0400 Date: Wed, 2 May 2001 21:18:00 +0300 From: Matti Aarnio To: Jim Gettys Cc: linux-kernel@vger.kernel.org Subject: Re: X15 alpha release: as fast as TUX but in user space (fwd) Message-ID: <20010502211800.X805@mea-ext.zmailer.org> In-Reply-To: <200104292116.f3TLGhu07016@pachyderm.pa.dec.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200104292116.f3TLGhu07016@pachyderm.pa.dec.com>; from jg@pa.dec.com on Sun, Apr 29, 2001 at 02:16:43PM -0700 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Apr 29, 2001 at 02:16:43PM -0700, Jim Gettys wrote: ... > "X is an exercise in avoiding system calls". I think I said this around > 1984-1985. > - Jim I think that applies to all really high-performance servers. Definitely it applies to ZMailer, which before did do time(2) some 1000-20000 times per second during some high activity bursts (limited essentially by the syscall speed). These days there is shared memory segment into which a server process updates the time value some 2-5 times per sec, and the consumer reads that -- likely now the consumer bursts peak beyond 100 000 reads. I think I took the idea from Interactive IX/386, which had magic global segment mapped to all userspaces for few fast common tasks, including gettimeofday() data. That was around 1990, or a bit before (I switched to Linux soon after.) Where they got the idea from, that I haven't checked. The basic algorithms and ideas we employ to do these wonders are also described by Knuth in his "The Art of Computer Programming" series. And usually he is referring to some earlier publications. > -- > Jim Gettys > Technology and Corporate Development > Compaq Computer Corporation > jg@pa.dec.com /Matti Aarnio