From owner-freebsd-current@FreeBSD.ORG Wed Apr 5 20:39:12 2006 Return-Path: X-Original-To: freebsd-current@freebsd.org Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id D882A16A41F for ; Wed, 5 Apr 2006 20:39:12 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from server.baldwin.cx (66-23-211-162.clients.speedfactory.net [66.23.211.162]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4D24A43D67 for ; Wed, 5 Apr 2006 20:39:08 +0000 (GMT) (envelope-from jhb@freebsd.org) Received: from localhost (john@localhost [127.0.0.1]) by server.baldwin.cx (8.13.4/8.13.4) with ESMTP id k35Kd17l063685; Wed, 5 Apr 2006 16:39:03 -0400 (EDT) (envelope-from jhb@freebsd.org) From: John Baldwin To: freebsd-current@freebsd.org Date: Wed, 5 Apr 2006 16:38:57 -0400 User-Agent: KMail/1.9.1 References: <20060405003358.GA83600@tin.it> In-Reply-To: <20060405003358.GA83600@tin.it> MIME-Version: 1.0 Content-Disposition: inline Message-Id: <200604051638.59800.jhb@freebsd.org> Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Virus-Scanned: ClamAV 0.87.1/1376/Wed Apr 5 01:51:25 2006 on server.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-4.0 required=4.2 tests=ALL_TRUSTED,AWL,BAYES_00 autolearn=ham version=3.1.0 X-Spam-Checker-Version: SpamAssassin 3.1.0 (2005-09-13) on server.baldwin.cx Cc: Luigi Rizzo Subject: Re: Interesting data on network interrupt - part II X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 05 Apr 2006 20:39:12 -0000 On Tuesday 04 April 2006 20:33, Paolo Pisati wrote: > Hi, > > i updated my work on interrupt profiling with sone new > experiments. > > In total we have now: > > -FreeBSD 4 PIC (no asm part) > -FreeBSD 7 APIC > -FreeBSD 7 PIC > -FreeBSD 7 PREE APIC > -FreeBSD 7 APIC JHB > > Some quick comments: > > -PIC is much slower in masking interrupt (7k in PIC vs 3k in APIC) > -PREE let new thread save less than 500 ticks of 'queue' while > preempted threads are often resumed after a lot > -JHB patch shaved 2.5k ticks in interrupt masking op > > For graphs, data and more comments: > > http://mercurio.sm.dsi.unimi.it/~pisati/interrupt/ I'll commit the patch then. :) One thing you might try to do to better measure the effects of preemption is to generate kernel work so that the bge interrupts occur while the current thread is in the kernel rather than in userland. In that case preemption should provide much lower latency for interrupt handlers, as w/o preemption, an interrupt in kernel mode won't run the ithread until either curthread blocks or returns to userland. -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org