Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262282AbVBBLOX (ORCPT ); Wed, 2 Feb 2005 06:14:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262268AbVBBLOX (ORCPT ); Wed, 2 Feb 2005 06:14:23 -0500 Received: from mail.suse.de ([195.135.220.2]:15254 "EHLO Cantor.suse.de") by vger.kernel.org with ESMTP id S262282AbVBBLOJ (ORCPT ); Wed, 2 Feb 2005 06:14:09 -0500 Subject: Re: [PATCH 1/8] lib/sort: Heapsort implementation of sort() From: Andreas Gruenbacher To: Herbert Xu Cc: mpm@selenic.com, Andrew Morton , "linux-kernel@vger.kernel.org" In-Reply-To: References: Content-Type: text/plain Organization: SUSE Labs Message-Id: <1107342847.21040.18.camel@winden.suse.de> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 Date: Wed, 02 Feb 2005 12:14:07 +0100 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1420 Lines: 40 On Wed, 2005-02-02 at 11:50, Herbert Xu wrote: > Andreas Gruenbacher wrote: > > > > static inline void swap(void *a, void *b, int size) > > { > > if (size % sizeof(long)) { > > char t; > > do { > > t = *(char *)a; > > *(char *)a++ = *(char *)b; > > *(char *)b++ = t; > > } while (--size > 0); > > } else { > > long t; > > do { > > t = *(long *)a; > > *(long *)a = *(long *)b; > > *(long *)b = t; > > size -= sizeof(long); > > } while (size > sizeof(long)); > > } > > } > > What if a/b aren't aligned? That would be the case if the entire array was unaligned, or (size % sizeof(long)) != 0. If people sort arrays that are unaligned even though the element size is a multiple of sizeof(long) (or sizeof(u32) as Matt proposes), they are just begging for bad performance. Otherwise, we're doing byte-wise swap anyway. -- Andreas Gruenbacher SUSE Labs, SUSE LINUX GMBH - 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/