From owner-freebsd-stable@FreeBSD.ORG Tue Nov 8 11:26:15 2005 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 4B49516A41F for ; Tue, 8 Nov 2005 11:26:15 +0000 (GMT) (envelope-from michael.schuh@gmail.com) Received: from nproxy.gmail.com (nproxy.gmail.com [64.233.182.192]) by mx1.FreeBSD.org (Postfix) with ESMTP id A685543D45 for ; Tue, 8 Nov 2005 11:26:14 +0000 (GMT) (envelope-from michael.schuh@gmail.com) Received: by nproxy.gmail.com with SMTP id l24so193765nfc for ; Tue, 08 Nov 2005 03:26:13 -0800 (PST) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=stjTy/utyAYlkngVPhNu8vDNDTCW73aOsMnw8/SpxqVKvbWbhR8YhtX5Jd0qGD2EY/hg7XzNqHUl/tpP7/uonRKNhOBfWouOBOgXd/OQQb7j+4uOe90sEPh9pmgxFTsxte7y6UDoBiIcCHkA8awR3N2Sxvu7g/QkjkIW/9bUnEY= Received: by 10.48.144.1 with SMTP id r1mr1675981nfd; Tue, 08 Nov 2005 03:26:13 -0800 (PST) Received: by 10.48.43.6 with HTTP; Tue, 8 Nov 2005 03:26:13 -0800 (PST) Message-ID: <1dbad3150511080326p62ec11at@mail.gmail.com> Date: Tue, 8 Nov 2005 12:26:13 +0100 From: Michael Schuh To: freebsd-stable@freebsd.org In-Reply-To: <1dbad3150511070339k15a99854r@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline References: <1dbad3150511070339k15a99854r@mail.gmail.com> Subject: Re: timecounter and Hz quality in kern RELENG_6 X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 08 Nov 2005 11:26:15 -0000 Hello, thanks to Oliver and Michael for explain me the "mechanics" behind timecounter and "Hz quality". I have send the question, why i have to wonder about different IRQ-Counts but same HZ. It is really thaat HZ on both machines is the same. I have only knowed the old behavior. I set the HZ over Options HZ in my Kernelconfig, and then i could see that the IRQCount's on clk are alwas the same value as HZ +- a few tics. So that i have thinked ( and feeled on busy machines) that the IRQ-work is more smooth and they are less holes in responsitivity if the HZ is going to an Value > 1000. So i have alwas set HZ to 2000 on every machine. If i have the answers and the "mechanics" behind timecounter and "Hz quality" right understand, so i have no more modify the HZ Value to become an smooth polling of the interupts. if i be right the smooth behavior comes with the calculation from "Hz quality". Please correct me if i am wrong. thanks to all and best regards michael 2005/11/7, Michael Schuh : > Hello, > > i be very surprised about the performance of RELENG_6. > Congratulations to the entire Team for this very good work. > > Now i have 2 Machines installed with 6.0-RC1, and i have seen that on > both machines the Hz is differntly with GENERIC-Kernel. > Machine A is an Sempron 2400+ that runs as 2500+ > (i have tuned the clock to best RAM-Performace) > Machine B is an Duron 700MHz > > On Machine A i got an Hz from 2000 effectively > systat -vmstat 1 show me 2000 IRQ/s on clk > sysctl say's 1000....i think, but not sure > > On Machine B i got an Hz from 1000 effectively > systat-vmstat 1 show me 1000 IRQ/s on clk > > After digging in the source i have found that timec.c have an routine for > computing the so called "Hz quality". > > Can anyone explain me the "mystics" behind Hz quality, > and why or how this quality is computed and what are the > efforts? > > My knowledge is not deep enough to know these details. > > thanks > > best regards > > michael >