From owner-freebsd-stable@FreeBSD.ORG Thu Dec 21 23:29:14 2006 Return-Path: X-Original-To: freebsd-stable@FreeBSD.ORG Delivered-To: freebsd-stable@FreeBSD.ORG Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 1C0EE16A412 for ; Thu, 21 Dec 2006 23:29:14 +0000 (UTC) (envelope-from markir@paradise.net.nz) Received: from smtp5.clear.net.nz (smtp5.clear.net.nz [203.97.33.68]) by mx1.freebsd.org (Postfix) with ESMTP id D4BFE13C45F for ; Thu, 21 Dec 2006 23:29:13 +0000 (UTC) (envelope-from markir@paradise.net.nz) Received: from [192.168.1.11] (121-72-65-158.dsl.telstraclear.net [121.72.65.158]) by smtp5.clear.net.nz (CLEAR Net Mail) with ESMTP id <0JAN00AE9D8OC840@smtp5.clear.net.nz> for freebsd-stable@FreeBSD.ORG; Fri, 22 Dec 2006 12:29:12 +1300 (NZDT) Date: Fri, 22 Dec 2006 12:29:11 +1300 From: Mark Kirkwood In-reply-to: <200612211353.kBLDrG1M085224@lurza.secnetix.de> To: freebsd-stable@FreeBSD.ORG, markir@paradise.net.nz Message-id: <458B18C7.6010406@paradise.net.nz> MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 7bit References: <200612211353.kBLDrG1M085224@lurza.secnetix.de> User-Agent: Thunderbird 1.5.0.8 (X11/20061129) Cc: Subject: Re: Cached file read performance with 6.2-PRERELEASE X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 21 Dec 2006 23:29:14 -0000 Oliver Fromme wrote: > Mark Kirkwood wrote: > > Exactly, that's why I did the comparison - I think you missed the part > > where I mentioned the 2 systems were *identical* with respect to cpus, > > memory, mobo - in fact even the power supplies are identical too! > > So I assume your benchmark measured the performance of the > zero and null devices under FreeBSD and Linux. > No - that was peripheral to the benchmark, and I should not have sent that message 'cause actually I've taken dev/zero and /dev/null *out* of the picture - check earlier messages with the .c prog attached, I'm using read(2) and lseek(2) to access a "real" file, that just happens (i.e. has been arranged) to be cached! > This is a quote from the "cstream" docs: "These special > devices speed varies greatly among operating systems, > redirecting from it isn't appropriate benchmarking and > a waste of resources anyway." > > I suggest you try cstream (ports/misc/cstream) instead of > dd. It supports built-in zero creation and data sink, so > you don't have to use the zero and null devices at all, > eliminating their overhead. It would be interesting how > that will change your benchmark numbers. > Thanks - I was suspicious of these special files, but had no evidence! Cheers Mark