From owner-freebsd-hackers Wed May 1 13:21:46 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id NAA16297 for hackers-outgoing; Wed, 1 May 1996 13:21:46 -0700 (PDT) Received: from irz301.inf.tu-dresden.de (irz301.inf.tu-dresden.de [141.76.1.11]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id NAA16288 for ; Wed, 1 May 1996 13:21:38 -0700 (PDT) Received: from sax.sax.de by irz301.inf.tu-dresden.de (8.6.12/8.6.12-s1) with ESMTP id WAA16708 for ; Wed, 1 May 1996 22:20:53 +0200 Received: by sax.sax.de (8.6.11/8.6.12-s1) with UUCP id WAA15768 for freebsd-hackers@freebsd.org; Wed, 1 May 1996 22:20:53 +0200 Received: (from j@localhost) by uriah.heep.sax.de (8.7.5/8.6.9) id WAA10967 for freebsd-hackers@freebsd.org; Wed, 1 May 1996 22:17:33 +0200 (MET DST) From: J Wunsch Message-Id: <199605012017.WAA10967@uriah.heep.sax.de> Subject: Re: lmbench IDE anomaly To: freebsd-hackers@freebsd.org (FreeBSD hackers) Date: Wed, 1 May 1996 22:17:32 +0200 (MET DST) Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) In-Reply-To: <199605010947.LAA08814@labinfo.iet.unipi.it> from Luigi Rizzo at "May 1, 96 11:47:43 am" X-Phone: +49-351-2012 669 X-PGP-Fingerprint: DC 47 E6 E4 FF A6 E9 8F 93 21 E0 7D F9 12 D6 4E X-Mailer: ELM [version 2.4ME+ PL15 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk As Luigi Rizzo wrote: > The original poster was doing a couple of lmdd from /dev/rwd0a, the raw > device. Does disksort get in the way in this case ? disksort() is always called, though Bruce pointed out that it's a nop in recent systems. > BTW, running a number of dd on /dev/wd0a works *much* better, you get > almost n times the bandwidth at least with up to 5 instances, what I > tried. You're measuring your buffer cache. Better use random() instead, it will be more accurate. ;-) -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)