From owner-freebsd-hackers@FreeBSD.ORG Fri Oct 24 14:12:02 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 7D02916A4B3 for ; Fri, 24 Oct 2003 14:12:02 -0700 (PDT) Received: from smtp6.Stanford.EDU (smtp6.Stanford.EDU [171.67.16.33]) by mx1.FreeBSD.org (Postfix) with ESMTP id ACEE943FF7 for ; Fri, 24 Oct 2003 14:11:58 -0700 (PDT) (envelope-from tedu@stanford.edu) Received: from saga0.Stanford.EDU (saga0.Stanford.EDU [171.64.15.130]) by smtp6.Stanford.EDU (8.12.10/8.12.10) with ESMTP id h9OLBrNs021678; Fri, 24 Oct 2003 14:11:55 -0700 (PDT) Date: Fri, 24 Oct 2003 14:11:53 -0700 (PDT) From: Ted Unangst To: Michel TALON In-Reply-To: <20031024112740.GA20599@lpthe.jussieu.fr> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: freebsd-hackers@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: Fri, 24 Oct 2003 21:12:02 -0000 On Fri, 24 Oct 2003, Michel TALON wrote: > What is more interesting is to look at the actual benchmark results in > http://bulk.fefe.de/scalability/ > in particular the section about mmap benchmarks, the only one where > OpenBSD shines. However as soon as touching pages is benchmarked > OpenBSD fails very much. look closer. openbsd's "touch page" times are identical to what you'd expect a disk access to be. the pages aren't cached, they're read from disk. so compared to systems that don't read from disk, it looks pretty bad. a 5 line patch to fix the benchmark so that the file actually is cached on openbsd results in performance much in line with freebsd/linux. -- "People have criticized me because my security detail is larger than the president's. But you must ask yourself: are there more people who want to kill me than who want to kill the president? I can assure you there are." - M. Barry, Mayor of Washington, DC