From owner-freebsd-hackers@FreeBSD.ORG Sun Nov 2 21:21:12 2003 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id CE15F16A4CE; Sun, 2 Nov 2003 21:21:12 -0800 (PST) Received: from VARK.homeunix.com (adsl-68-123-40-77.dsl.pltn13.pacbell.net [68.123.40.77]) by mx1.FreeBSD.org (Postfix) with ESMTP id C18CA43F75; Sun, 2 Nov 2003 21:21:11 -0800 (PST) (envelope-from das@FreeBSD.ORG) Received: from VARK.homeunix.com (localhost [127.0.0.1]) by VARK.homeunix.com (8.12.9/8.12.9) with ESMTP id hA35KBen071644; Sun, 2 Nov 2003 21:20:11 -0800 (PST) (envelope-from das@FreeBSD.ORG) Received: (from das@localhost) by VARK.homeunix.com (8.12.9/8.12.9/Submit) id hA35KA9e071643; Sun, 2 Nov 2003 21:20:10 -0800 (PST) (envelope-from das@FreeBSD.ORG) Date: Sun, 2 Nov 2003 21:20:10 -0800 From: David Schultz To: Vivek Pai Message-ID: <20031103052010.GA71583@VARK.homeunix.com> Mail-Followup-To: Vivek Pai , Dag-Erling@FreeBSD.ORG,, freebsd-hackers@FreeBSD.ORG, Q , Kris Kennaway References: <1066789354.21430.39.camel@boxster.onthenet.com.au> <20031022082953.GA69506@rot13.obsecurity.org> <1066816287.25609.34.camel@boxster.onthenet.com.au> <20031022095754.GA70026@rot13.obsecurity.org> <1066820436.25609.93.camel@boxster.onthenet.com.au> <20031026052854.GA20701@VARK.homeunix.com> <3FA2C63C.5000900@cs.princeton.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3FA2C63C.5000900@cs.princeton.edu> cc: Q cc: freebsd-hackers@FreeBSD.ORG cc: Kris Kennaway cc: iso-8859-1?Q?Sm=F8rgrav?= cc: Dag-Erling@FreeBSD.ORG cc: "=?us-ascii@FreeBSD.ORG"@FreeBSD.ORG Subject: Re: Some mmap observations compared to Linux 2.6/OpenBSD X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 03 Nov 2003 05:21:12 -0000 On Fri, Oct 31, 2003, Vivek Pai wrote: > Take a look at Figure 6, page 9 in the following: > http://www.cs.princeton.edu/~yruan/DeBox/debox.pdf > > On a 1GHz box with 1GB of memory, we were spending > 4-5 milliseconds per mmap call, and that was limiting > the throughput of our server on SpecWeb99. > > Figure 9 on page 11 shows that just getting rid of the > mmap/munmap/mincore calls in this server got us a 50% > performance boost on a fairly complicated workload. The > SpecWeb99 workload was modeled after several web sites, > so this might actually be a performance problem in the > real world. > > If you look at figure 11, page 12, you'll see that with > various improvements, our server's median latency dropped to > less than 1ms. An mmap time of several milliseconds would > kill that benefit. Okay, I guess SpecWeb99 is ``real world'' enough for me to justify the assertion that there is an mmap() performance problem. Just out of curiosity, how many regions did SpecWeb99 map? (i.e. what does 'dd if=/proc/$pid/map bs=64k count=1 | wc -l' give?)