From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965620Ab2EQVfU (ORCPT ); Thu, 17 May 2012 17:35:20 -0400 Received: from casper.infradead.org ([85.118.1.10]:45873 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932224Ab2EQVfS convert rfc822-to-8bit (ORCPT ); Thu, 17 May 2012 17:35:18 -0400 Message-ID: <1337290512.4281.91.camel@twins> Subject: Re: [PATCH 1/2] lib: Proportions with flexible period From: Peter Zijlstra To: Jan Kara Cc: Wu Fengguang , LKML , linux-mm@kvack.org Date: Thu, 17 May 2012 23:35:12 +0200 In-Reply-To: <1337096583-6049-2-git-send-email-jack@suse.cz> References: <1337096583-6049-1-git-send-email-jack@suse.cz> <1337096583-6049-2-git-send-email-jack@suse.cz> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2012-05-15 at 17:43 +0200, Jan Kara wrote: > + if (numerator > ((long long)denominator) * max_frac / 100) Does that even compile on 32bit archs? Operator precedence is *,/ left-to-right, so that's: long long t1 = (long long)denom * max_frac long long t2 = t1 / 100; Which is a 64bit signed division. There's a reason I used that max_prop_frac thing you removed, it avoids having to do the division at all and allows a mult and shift instead.