Date: Sat, 7 Oct 1995 22:33:58 -0400 (EDT) From: Chuck Robey <chuckr@eng.umd.edu> To: Stefan Esser <se@zpr.uni-koeln.de> Cc: "Kenneth D. Merry" <ken@rflab1.gtri.gatech.edu>, hackers@freebsd.org Subject: Re: VLB Disk Controllers Message-ID: <Pine.SUN.3.91.951007223011.13390B-100000@mocha.eng.umd.edu> In-Reply-To: <199510072335.AA14520@Sysiphos>
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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 <se@ZPR.Uni-Koeln.DE> > ----------------------------+----------------------------------------------- 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! ----------------------------+-----------------------------------------------
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