From owner-freebsd-current@FreeBSD.ORG Sat Sep 17 21:33:47 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 20D3D16A41F for ; Sat, 17 Sep 2005 21:33:47 +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 9B90743D45 for ; Sat, 17 Sep 2005 21:33:44 +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 j8HLXh59010227 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sat, 17 Sep 2005 17:33:43 -0400 (EDT) Received: (from gallatin@localhost) by grasshopper.cs.duke.edu (8.12.9p2/8.12.9/Submit) id j8HLXcRK098467; Sat, 17 Sep 2005 17:33:38 -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: <17196.35762.395155.325627@grasshopper.cs.duke.edu> Date: Sat, 17 Sep 2005 17:33:38 -0400 (EDT) To: joseph.koshy@gmail.com In-Reply-To: <20050917102846.7bf26a56.lehmann@ans-netz.de> 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> 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: Sat, 17 Sep 2005 21:33:47 -0000 Oliver Lehmann writes: > Joseph Koshy wrote: > > > ol> Wow, that update to BETA4 did the trick! While running > > ol> SCHED_4BSD: > > > > Fantastic! What is the profile like with the new 4BSD kernel? > > http://pofo.de/tmp/gprof.4bsd.3 I don't know the disk codepath very well, but the samples look a little suspect. We're copying a lot of data into and out of the kernel, so I would expect the majority of non disk wait time would be spent simply copying out the zero-filled pages, and copying them back in (AFAIK, dd uses read/write). Where is the time spent in read, write, uiomove, bcopy? What about ionode allocations, etc? And why do things like g_bsd_modify and g_bsd_ioctl rank so high? Aren't those only used when dealing with disklabels? BTW, I *love* that we've got access to the hw counters, and an easy way to do low-overhead profiling of the kernel. Drew