Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263128AbUC2UB5 (ORCPT ); Mon, 29 Mar 2004 15:01:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263125AbUC2UA2 (ORCPT ); Mon, 29 Mar 2004 15:00:28 -0500 Received: from e2.ny.us.ibm.com ([32.97.182.102]:7057 "EHLO e2.ny.us.ibm.com") by vger.kernel.org with ESMTP id S263127AbUC2UAK (ORCPT ); Mon, 29 Mar 2004 15:00:10 -0500 Date: Mon, 29 Mar 2004 11:57:54 -0800 (PST) From: Sridhar Samudrala X-X-Sender: sridhar@localhost.localdomain To: Jeff Garzik cc: Edgar Toernig , davem@redhat.com, linux-kernel@vger.kernel.org, netdev@oss.sgi.com Subject: Re: [PATCH] Consolidate multiple implementations of jiffies-msecs conversions. In-Reply-To: <40647E65.7020903@pobox.com> Message-ID: References: <20040326014403.39388cb8.froese@gmx.de> <40647E65.7020903@pobox.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2101 Lines: 63 On Fri, 26 Mar 2004, Jeff Garzik wrote: > Sridhar Samudrala wrote: > > On Fri, 26 Mar 2004, Edgar Toernig wrote: > > > > > >>Sridhar Samudrala wrote: > >> > >>>The following patch to 2.6.5-rc2 consolidates 6 different implementations > >>>of msecs to jiffies and 3 different implementation of jiffies to msecs. > >>>All of them now use the generic msecs_to_jiffies() and jiffies_to_msecs() > >>>that are added to include/linux/time.h > >>>[...] > >>>-#define MSECS(ms) (((ms)*HZ/1000)+1) > >>>-return (((ms)*HZ+999)/1000); > >>>+return (msecs / 1000) * HZ + (msecs % 1000) * HZ / 1000; > >> > >>Did you check that all users of the new version will work correctly > >>with your rounding? Explicit round-up of delays is often required, > >>especially when talking to hardware... > > > > > > I don't see any issues with the 2.6 default HZ value of 1000 as they become > > no-ops and there is no need for any rounding. > > I guess you are referring to cases when HZ < 1000(ex: 100) and msecs is > > less than 10. In those cases, the new version returns 0, whereas some of the > > older versions return 1. > > We'll definitely want to return 1 rather than zero, for the uses in my > drivers, at least... I have modified msecs_to_jiffies() to do the proper rounding when HZ=100. Do these work better? static inline unsigned long msecs_to_jiffies(unsigned long msecs) { #if 1000 % HZ == 0 return (msecs + ((1000 / HZ) - 1)) / (1000 / HZ); #elif HZ % 1000 == 0 return msecs * (HZ / 1000); #else return (msecs / 1000) * HZ + (msecs % 1000) * HZ / 1000; #endif } static inline unsigned long jiffies_to_msecs(unsigned long jiffs) { #if 1000 % HZ == 0 return jiffs * (1000 / HZ); #elif HZ % 1000 == 0 return jiffs / (HZ / 1000); #else return (jiffs / HZ) * 1000 + (jiffs % HZ) * 1000 / HZ; #endif } Thanks Sridhar - 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/