From owner-freebsd-bugs@FreeBSD.ORG Mon Nov 19 11:50:02 2007 Return-Path: Delivered-To: freebsd-bugs@hub.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id A4F6C16A419 for ; Mon, 19 Nov 2007 11:50:02 +0000 (UTC) (envelope-from gnats@FreeBSD.org) Received: from freefall.freebsd.org (freefall.freebsd.org [IPv6:2001:4f8:fff6::28]) by mx1.freebsd.org (Postfix) with ESMTP id 8962E13C461 for ; Mon, 19 Nov 2007 11:50:02 +0000 (UTC) (envelope-from gnats@FreeBSD.org) Received: from freefall.freebsd.org (gnats@localhost [127.0.0.1]) by freefall.freebsd.org (8.14.1/8.14.1) with ESMTP id lAJBo2fo045965 for ; Mon, 19 Nov 2007 11:50:02 GMT (envelope-from gnats@freefall.freebsd.org) Received: (from gnats@localhost) by freefall.freebsd.org (8.14.1/8.14.1/Submit) id lAJBo2mt045964; Mon, 19 Nov 2007 11:50:02 GMT (envelope-from gnats) Resent-Date: Mon, 19 Nov 2007 11:50:02 GMT Resent-Message-Id: <200711191150.lAJBo2mt045964@freefall.freebsd.org> Resent-From: FreeBSD-gnats-submit@FreeBSD.org (GNATS Filer) Resent-To: freebsd-bugs@FreeBSD.org Resent-Reply-To: FreeBSD-gnats-submit@FreeBSD.org, Heikki Suonsivu Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E7E3716A419 for ; Mon, 19 Nov 2007 11:46:09 +0000 (UTC) (envelope-from hsu@joutseno.wlansystems.com) Received: from joutseno.wlansystems.com (joutseno.wlansystems.com [212.16.100.99]) by mx1.freebsd.org (Postfix) with ESMTP id 4FE9113C45D for ; Mon, 19 Nov 2007 11:46:09 +0000 (UTC) (envelope-from hsu@joutseno.wlansystems.com) Received: from joutseno.wlansystems.com (localhost [127.0.0.1]) by joutseno.wlansystems.com (8.14.2/8.14.2) with ESMTP id lAJ9cwbn027012 for ; Mon, 19 Nov 2007 11:38:58 +0200 (EET) (envelope-from hsu@joutseno.wlansystems.com) Received: (from root@localhost) by joutseno.wlansystems.com (8.14.2/8.14.2/Submit) id lAJ9cwgR027011; Mon, 19 Nov 2007 11:38:58 +0200 (EET) (envelope-from hsu) Message-Id: <200711190938.lAJ9cwgR027011@joutseno.wlansystems.com> Date: Mon, 19 Nov 2007 11:38:58 +0200 (EET) From: Heikki Suonsivu To: FreeBSD-gnats-submit@FreeBSD.org X-Send-Pr-Version: 3.113 Cc: Subject: kern/118120: HZ value on slow computers X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Heikki Suonsivu List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 19 Nov 2007 11:50:02 -0000 >Number: 118120 >Category: kern >Synopsis: HZ value on slow computers >Confidential: no >Severity: serious >Priority: medium >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: change-request >Submitter-Id: current-users >Arrival-Date: Mon Nov 19 11:50:01 UTC 2007 >Closed-Date: >Last-Modified: >Originator: hsu@bbnetworks.net >Release: FreeBSD 6.2-STABLE i386 >Organization: bbnetworks.net >Environment: System: FreeBSD ranta.suonsivu.net 6.2-STABLE FreeBSD 6.2-STABLE #3: Sat Nov 17 15:33:51 EET 2007 root@ranta.suonsivu.net:/usr/obj/usr/src/sys/EBOX2300 i386 This is relevant to slow computers, such as anything based on SoC things, Sis550, Geode, very old computers. >Description: HZ was bumped to 1000 couple of years ago. This is fine for quick computers, but becomes a problem on old computers and various embedded devices. On Vortex86 cpu at 200MHz, and HZ set to 1000, with DUMMYNET and IPFW built into the kernel, cpu seems to spend around 12-14% of time in interrupt and overall performance is really low. >How-To-Repeat: Install FreeBSD on a slow computer. Try a 486, old pentiums, anything Sis550 or Geode based. Use a kernel with all firewall, dummynet and other heavy networking options on. >Fix: HZ should probably be dynamic, based on cpu, rather than a fixed value in kernel config. Workaround is setting HZ in loader.conf >Release-Note: >Audit-Trail: >Unformatted: