Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422719AbWBOK66 (ORCPT ); Wed, 15 Feb 2006 05:58:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751146AbWBOK66 (ORCPT ); Wed, 15 Feb 2006 05:58:58 -0500 Received: from scrub.xs4all.nl ([194.109.195.176]:33159 "EHLO scrub.xs4all.nl") by vger.kernel.org with ESMTP id S1751137AbWBOK66 (ORCPT ); Wed, 15 Feb 2006 05:58:58 -0500 Date: Wed, 15 Feb 2006 11:58:56 +0100 (CET) From: Roman Zippel X-X-Sender: roman@scrub.home To: Ulrich Windl cc: linux-kernel@vger.kernel.org Subject: Re: time patches by Roman Zippel In-Reply-To: <43F2E59D.24184.A70C2D5@Ulrich.Windl.rkdvmks1.ngate.uni-regensburg.de> Message-ID: References: <43F1F2B4.7205.6BBE301@Ulrich.Windl.rkdvmks1.ngate.uni-regensburg.de> <43F2E59D.24184.A70C2D5@Ulrich.Windl.rkdvmks1.ngate.uni-regensburg.de> MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="-1463811837-67307697-1140001136=:30994" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1570 Lines: 42 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. ---1463811837-67307697-1140001136=:30994 Content-Type: TEXT/PLAIN; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Hi, On Wed, 15 Feb 2006, Ulrich Windl wrote: > > > Assuming 1024Hz interrupt frequency: > > > (1=B5s * 1000) / 1024 =3D=3D 0ns; 0 * 1024 =3D=3D 0=B5s, not 1=B5s > > > (2=B5s * 1000) / 1024 =3D=3D 1ns; 1 * 1024 =3D=3D 1.024=B5s, not 2=B5= s > >=20 > > Ok, I didn't put much effort into optimizing it for uncommon HZ values.= =20 > > Why is it so important? It's currently unused on any Linux machine=20 > > synchronized via NTP. >=20 > Roman, >=20 > how do you know? When using "disable kernel", NTP relies on adjtime() to = adjust=20 > the time. Some people even prefer that, because the algorithms do floatin= g point=20 > math in user space instead of fixed-point maths in kernel space. This still requires they choose an uncommon HZ value, which is not really= =20 likely. Anyway, it's not really difficult to add the remainder to=20 time_adj_curr. Since the adjtime() has only a usec resolution and this=20 rounding error is only 1 usec, I didn't consider it to be that important. bye, Roman ---1463811837-67307697-1140001136=:30994-- - 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/