From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750784AbWBLOyb (ORCPT ); Sun, 12 Feb 2006 09:54:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750755AbWBLOyb (ORCPT ); Sun, 12 Feb 2006 09:54:31 -0500 Received: from zproxy.gmail.com ([64.233.162.207]:30822 "EHLO zproxy.gmail.com") by vger.kernel.org with ESMTP id S1750784AbWBLOya (ORCPT ); Sun, 12 Feb 2006 09:54:30 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:mime-version:content-type; b=ZQriBcK8dBf8QWa/I+ghLB6ourdZKMS7bXLunevLSMHOZXcmnvfQXgE2lq8D3sIyVwugW9CJiR9oLNxZs5pKUeXG15EAhh/oLEbF5RShdGiWj5bRDayQM6bn1HLmpsGvJWsnVQQj51A2cM3r/g9fqlc7U2yVvtplVuwbJTzpacc= Message-ID: Date: Sun, 12 Feb 2006 16:54:29 +0200 From: Hai Zaar To: linux-kernel@vger.kernel.org Subject: setting CONFIG_HZ=2000 screws up ntpd MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_1964_31653385.1139756069738" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org ------=_Part_1964_31653385.1139756069738 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Dear list, I use attached patch to speed up HZ from 1000 to 2000. I use this hack starting from kernel 2.6.7 and I have not experienced any particular problems. Recently I've started to use NTP and have noticed that ntp client loose synchronization, if this patch is applied, i.e. it connects, synchronizes, and then after a few polls, jitter just jumps to 5 digit number. I've rechecked the behavior on the kernel 2.6.11 and results are the same - applied patch just "skews up" ntpd, while there are no any problems with vanilla kernels. Is the patch incorrect in any way? -- Zaar ------=_Part_1964_31653385.1139756069738 Content-Type: text/x-patch; name=kernel-2.6.15-2000HZ-2.patch; charset=us-ascii Content-Transfer-Encoding: 7bit X-Attachment-Id: f_ejlh24ya Content-Disposition: attachment; filename="kernel-2.6.15-2000HZ-2.patch" The patch ajusts kernel internal clock timer to 2000HZ instead of 1000HZ. This is required to decrease response time of some drivers (currently rocket.ko). Author: Igor Yanover Crafted for 2.6.15 by: Michael Goldman --- kernel-2.6.15/include/linux/jiffies.h.orig 2006-02-07 12:59:20.000000000 +0200 +++ kernel-2.6.15/include/linux/jiffies.h 2006-02-07 13:00:50.000000000 +0200 @@ -38,6 +38,8 @@ # define SHIFT_HZ 9 #elif HZ >= 768 && HZ < 1536 # define SHIFT_HZ 10 +#elif HZ >= 1536 && HZ < 3072 +# define SHIFT_HZ 11 #else # error You lose. #endif --- kernel-2.6.15/kernel/Kconfig.hz.orig 2006-01-03 05:21:10.000000000 +0200 +++ kernel-2.6.15/kernel/Kconfig.hz 2006-02-07 18:44:03.000000000 +0200 @@ -36,6 +36,11 @@ 1000 HZ is the preferred choice for desktop systems and other systems requiring fast interactive responses to events. + config HZ_2000 + bool "2000 HZ" + help + 2000 HZ is hand crafted for software realtime. Use on your own risk. + endchoice config HZ @@ -43,4 +48,5 @@ default 100 if HZ_100 default 250 if HZ_250 default 1000 if HZ_1000 + default 2000 if HZ_2000 ------=_Part_1964_31653385.1139756069738--