Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265074AbUFGVYM (ORCPT ); Mon, 7 Jun 2004 17:24:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265079AbUFGVYL (ORCPT ); Mon, 7 Jun 2004 17:24:11 -0400 Received: from natsmtp00.rzone.de ([81.169.145.165]:41955 "EHLO natsmtp00.rzone.de") by vger.kernel.org with ESMTP id S265069AbUFGVXS (ORCPT ); Mon, 7 Jun 2004 17:23:18 -0400 Date: Mon, 7 Jun 2004 23:20:58 +0200 From: Dominik Brodowski To: john stultz Cc: lkml , george anzinger , greg kh , Chris McDermott Subject: [PATCH 1/3] mull'ify multiplication with HZ in __const_udelay() [Was: Re: Too much error in __const_udelay() ?] Message-ID: <20040607212058.GA23106@dominikbrodowski.de> Mail-Followup-To: Dominik Brodowski , john stultz , lkml , george anzinger , greg kh , Chris McDermott References: <1086419565.2234.133.camel@cog.beaverton.ibm.com> <20040605152326.GA11239@dominikbrodowski.de> <1086635568.2234.171.camel@cog.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1086635568.2234.171.camel@cog.beaverton.ibm.com> User-Agent: Mutt/1.5.6i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1244 Lines: 40 Move the multiplication of (loops_per_jiffy * xloops) with HZ into the "mull" asm operation. This increases the accuracy of the delay functions largely: n usec delay on a 1500000 BogoMIPS system: n before after 1 1000 ticks 1499 ticks 10 14000 ticks 14999 ticks n usec delay on a 100000 BogoMIPS system: n before after 1 0 ticks 99 ticks 10 0 ticks 999 ticks 100 9000 ticks 9999 ticks Signed-off-by: Dominik Brodowski diff -ruN linux-original/arch/i386/lib/delay.c linux/arch/i386/lib/delay.c --- linux-original/arch/i386/lib/delay.c 2004-06-07 22:01:46.608351088 +0200 +++ linux/arch/i386/lib/delay.c 2004-06-07 22:05:03.299449496 +0200 @@ -33,8 +33,8 @@ int d0; __asm__("mull %0" :"=d" (xloops), "=&a" (d0) - :"1" (xloops),"0" (current_cpu_data.loops_per_jiffy)); - __delay(xloops * HZ); + :"1" (xloops),"0" (current_cpu_data.loops_per_jiffy * HZ)); + __delay(xloops); } void __udelay(unsigned long usecs) - 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/