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, 10 Jan 2001 11:25:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 10 Jan 2001 11:25:22 -0500 Received: from nathan.polyware.nl ([193.67.144.241]:12549 "EHLO nathan.polyware.nl") by vger.kernel.org with ESMTP id ; Wed, 10 Jan 2001 11:25:11 -0500 Date: Wed, 10 Jan 2001 17:25:05 +0100 From: Pauline Middelink To: linux-kernel@vger.kernel.org Subject: Re: * 4 converted to << 2 for networking code Message-ID: <20010110172505.A32188@polyware.nl> Mail-Followup-To: Pauline Middelink , linux-kernel@vger.kernel.org In-Reply-To: <20010110174859.R7498@prosa.it> <3A5C778C.CFB363F3@didntduck.org> <20010110180322.T7498@prosa.it> <20010110161146.A3252@unthought.net> <20010110182546.U7498@prosa.it> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2i In-Reply-To: <20010110182546.U7498@prosa.it>; from antirez@invece.org on Wed, Jan 10, 2001 at 06:25:46PM +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 10 Jan 2001 around 18:25:46 +0100, antirez wrote: > On Wed, Jan 10, 2001 at 04:11:46PM +0100, Jakob ?stergaard wrote: > > On most processors <<2 is slower than *4. It's outright stupid to > > write <<2 when we mean *4 in order to optimize for one out of a > > gazillion supported architectures - even more so when the compiler > > for the one CPU where <<2 is faster, will actually generate a shift > > instead of a multiply as a part of the standard optimization. > > Hug, ok, so all the << 2 already in should be changed in *4. > My point is that it is better to use only << 2 or *4, selecting > the better form. Well, better not change things so they look like: #define MSG_BLA1 (1<<1) #define MSG_BLA2 (1*4) #define MSG_BLA3 (1<<3) as a result... :) Met vriendelijke groet, Pauline Middelink -- GPG Key fingerprint = 2D5B 87A7 DDA6 0378 5DEA BD3B 9A50 B416 E2D0 C3C2 For more details look at my website http://www.polyware.nl/~middelink - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/