From owner-freebsd-hackers Sat Oct 7 19:34:07 1995 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.6.12/8.6.6) id TAA11387 for hackers-outgoing; Sat, 7 Oct 1995 19:34:07 -0700 Received: from bacchus.eng.umd.edu (bacchus.eng.umd.edu [129.2.94.5]) by freefall.freebsd.org (8.6.12/8.6.6) with ESMTP id TAA11382 for ; Sat, 7 Oct 1995 19:34:04 -0700 Received: from mocha.eng.umd.edu (mocha.eng.umd.edu [129.2.98.16]) by bacchus.eng.umd.edu (8.7/8.7) with ESMTP id WAA23870; Sat, 7 Oct 1995 22:34:00 -0400 (EDT) Received: (chuckr@localhost) by mocha.eng.umd.edu (8.7/8.6.4) id WAA13550; Sat, 7 Oct 1995 22:33:59 -0400 (EDT) Date: Sat, 7 Oct 1995 22:33:58 -0400 (EDT) From: Chuck Robey To: Stefan Esser cc: "Kenneth D. Merry" , hackers@freebsd.org Subject: Re: VLB Disk Controllers In-Reply-To: <199510072335.AA14520@Sysiphos> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-hackers@freebsd.org Precedence: bulk On Sun, 8 Oct 1995, Stefan Esser wrote: > On Oct 7, 19:13, "Kenneth D. Merry" wrote: > } Subject: Re: VLB Disk Controllers > > } Adaptec 2842 on a i486DX4/100 VLB (QUANTUM XP34300) (Atlas, fast disk) > } output for disklatency /dev/rsd0: > } Command overhead is 567 usec (time_4096 = 1002, time_8192 = 1438) > } transfer speed is 9.40748e+06 bytes/sec > > Well, you beat me, though not by much :) > > But then, you used a DX4/100 ... > > Something I just noticed is the big difference > in results I get using /dev/rsd0 vs. /dev/rsd0a: > > # disklatency /dev/rsd0 > Command overhead is 719 usec (time_4096 = 1198, time_8192 = 1677) > transfer speed is 8.55617e+06 bytes/sec > > # disklatency /dev/rsd0a > Command overhead is 807 usec (time_4096 = 1272, time_8192 = 1738) > transfer speed is 8.80588e+06 bytes/sec I just did that 10 times in a row with my 2842, and reading differing over a 2:1 range. I think there's some windage here that makes your comparison suspect. Try it a few tries in a row on the same drive. > > Any ideas ??? > > STefan > > -- > Stefan Esser, Zentrum fuer Paralleles Rechnen Tel: +49 221 4706021 > Universitaet zu Koeln, Weyertal 80, 50931 Koeln FAX: +49 221 4705160 > ============================================================================== > http://www.zpr.uni-koeln.de/staff/esser/esser.html > ----------------------------+----------------------------------------------- Chuck Robey | Interests include any kind of voice or data chuckr@eng.umd.edu | communications topic, C programming, and Unix. 9120 Edmonston Ct #302 | Greenbelt, MD 20770 | I run Journey2 and n3lxx, both FreeBSD (301) 220-2114 | version 2.2 current -- and great FUN! ----------------------------+-----------------------------------------------