From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx129.postini.com [74.125.245.129]) by kanga.kvack.org (Postfix) with SMTP id 4AD066B0082 for ; Fri, 18 May 2012 10:33:29 -0400 (EDT) Date: Fri, 18 May 2012 16:33:15 +0200 From: Jan Kara Subject: Re: [PATCH 1/2] lib: Proportions with flexible period Message-ID: <20120518143315.GB6875@quack.suse.cz> References: <1337096583-6049-1-git-send-email-jack@suse.cz> <1337096583-6049-2-git-send-email-jack@suse.cz> <1337290512.4281.91.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1337290512.4281.91.camel@twins> Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: Jan Kara , Wu Fengguang , LKML , linux-mm@kvack.org On Thu 17-05-12 23:35:12, Peter Zijlstra wrote: > 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. Yeah, I misunderstood it's purpose when I read the code originally. I'll put it back to avoid the division since this is a hot path. Honza -- Jan Kara SUSE Labs, CR -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org