From owner-cvs-src@FreeBSD.ORG Thu Oct 20 14:34:51 2005 Return-Path: X-Original-To: cvs-src@freebsd.org Delivered-To: cvs-src@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id B902C16A421; Thu, 20 Oct 2005 14:34:51 +0000 (GMT) (envelope-from scottl@samsco.org) Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57]) by mx1.FreeBSD.org (Postfix) with ESMTP id A7A9A43D5A; Thu, 20 Oct 2005 14:34:49 +0000 (GMT) (envelope-from scottl@samsco.org) Received: from [192.168.1.105] (69-161-144-40.miamfl.adelphia.net [69.161.144.40]) (authenticated bits=0) by pooker.samsco.org (8.13.4/8.13.4) with ESMTP id j9KEYgjx073211; Thu, 20 Oct 2005 08:34:42 -0600 (MDT) (envelope-from scottl@samsco.org) Message-ID: <4357AAFE.2070002@samsco.org> Date: Thu, 20 Oct 2005 08:34:38 -0600 From: Scott Long User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.7.8) Gecko/20050615 X-Accept-Language: en-us, en MIME-Version: 1.0 To: John Baldwin References: <200510172310.j9HNAVPL013057@repoman.freebsd.org> <4355080C.302@samsco.org> <20051020145234.H99720@delplex.bde.org> <200510200958.09182.jhb@freebsd.org> In-Reply-To: <200510200958.09182.jhb@freebsd.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=2.0 required=3.8 tests=RCVD_IN_SORBS_DUL autolearn=no version=3.1.0 X-Spam-Level: * X-Spam-Checker-Version: SpamAssassin 3.1.0 (2005-09-13) on pooker.samsco.org Cc: src-committers@freebsd.org, Andrew Gallatin , Bruce Evans , cvs-src@freebsd.org, cvs-all@freebsd.org, David Xu Subject: Re: cvs commit: src/sys/amd64/amd64 cpu_switch.S machdep.c X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 20 Oct 2005 14:34:52 -0000 John Baldwin wrote: > On Thursday 20 October 2005 01:45 am, Bruce Evans wrote: > >>On Tue, 18 Oct 2005, Scott Long wrote: >>I use 100 and never downgraded to use 1000 except for testing how bad >>it is. The default number is now up to * 2 * HZ. >>E.g., it is 4000 on sledge.freebsd.org. While 4000 interrupts/sec can >>be handled easily by any new machine, 4000 is a disgustingly large >>number to use for clock interrupts. Have a look at vmstat -i output >>on almost any machine. On most machines in the freebsd cluster, the >>total number of interrupts is dominated by clock interrupts even with >>HZ = 100. > > > Note that on 4.x you don't get to see the interrupt counts for the hz + stathz > * (cpus - 1) IPIs for all the clock interrupts, so in real numbers, each CPU > has gone from hz + stathz to hz * 2 interrupts. However, the higher number > is offset by the fact that the interrupt handler for the lapic case doesn't > have to touch any hardware, and it also works much more reliably (getting > irq0 to work in APIC mode on some amd64 nvidia chipsets required several > quirks, and future motherboards will probably continue to require quirks > since Windows uses the APIC timer in APIC mode and doesn't require irq0 to > work in APIC mode). > I'm in complete argreement that using the APIC timer is the right thing to do, and I believe that we did some tests to show that the high interrupt rate didn't have an appreciable effect on performance. However, I'd like to revisit the HZ=1000 decision for 7-CURRENT. Scott