From owner-freebsd-current@FreeBSD.ORG Mon Sep 19 18:06:27 2005 Return-Path: X-Original-To: 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 61B7216A41F for ; Mon, 19 Sep 2005 18:06:27 +0000 (GMT) (envelope-from gallatin@cs.duke.edu) Received: from duke.cs.duke.edu (duke.cs.duke.edu [152.3.140.1]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4D9C443D53 for ; Mon, 19 Sep 2005 18:06:24 +0000 (GMT) (envelope-from gallatin@cs.duke.edu) Received: from grasshopper.cs.duke.edu (grasshopper.cs.duke.edu [152.3.145.30]) by duke.cs.duke.edu (8.13.4/8.13.4) with ESMTP id j8JI6N5L029538 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Mon, 19 Sep 2005 14:06:23 -0400 (EDT) Received: (from gallatin@localhost) by grasshopper.cs.duke.edu (8.12.9p2/8.12.9/Submit) id j8JI6FKD002403; Mon, 19 Sep 2005 14:06:15 -0400 (EDT) (envelope-from gallatin) From: Andrew Gallatin MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <17198.65047.682527.433172@grasshopper.cs.duke.edu> Date: Mon, 19 Sep 2005 14:06:15 -0400 (EDT) To: Scott Long In-Reply-To: <432CCEF5.2050608@samsco.org> References: <20050914194612.15692485.lehmann@ans-netz.de> <20050914222013.178dc4dc.lehmann@ans-netz.de> <84dead72050914135239514c49@mail.gmail.com> <20050915000053.448f251b.lehmann@ans-netz.de> <84dead7205091500152a7c25d1@mail.gmail.com> <20050915172005.072f4bdf.lehmann@ans-netz.de> <20050915181238.54b16b4b.lehmann@ans-netz.de> <84dead720509160921732e7f96@mail.gmail.com> <20050916184911.38e2739a.lehmann@ans-netz.de> <20050916225219.73b53cd0.lehmann@ans-netz.de> <84dead7205091619435c12b528@mail.gmail.com> <20050917102846.7bf26a56.lehmann@ans-netz.de> <17196.35762.395155.325627@grasshopper.cs.duke.edu> <432CCEF5.2050608@samsco.org> X-Mailer: VM 6.75 under 21.1 (patch 12) "Channel Islands" XEmacs Lucid Cc: current@freebsd.org Subject: Re: low(er) disk performance with sched_4bsd then with sched_ule 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: Mon, 19 Sep 2005 18:06:27 -0000 Scott Long writes: > I don't know if it's the case here or not, but GCC now does very > aggressive function inlining, so much so that it's nearly impossible > to look at a backtrace and figure out what the actual call path was. > Compiling with -O instead of the -O2 default turns off this 'feature' > (and I use that term quite liberally), so it might be useful to > recompile there kernel with 'CFLAGS= -O' in /etc/make.conf and see > if it changes the profiling numbers at all. If inlining were at fault, I would expect to see something which calls bcopy (copin/copyout or uiomove) have a lot of samples. > Also, I think that there was some talk last year about things like > preemption and fast interrupts screwing up certain kinds of profiling. > I don't recall if there was a solution to this, though. I wonder if this could be it. But I'm still not sure how they could interfere with a copyin/copyout in a process context.. Drew