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From: "John S. Dyson" <toor@dyson.iquest.net>
Message-Id: <199604101308.IAA00947@dyson.iquest.net>
Subject: Re: HDD cpu usage (IDE vs. SCSI).
To: se@ZPR.Uni-Koeln.DE (Stefan Esser)
Date: Wed, 10 Apr 1996 08:08:53 -0500 (EST)
Cc: bde@zeta.org.au, dutchman@spase.nl, freebsd-hackers@freebsd.org
In-Reply-To: <199604091900.AA05584@Sisyphos> from "Stefan Esser" at Apr 9, 96 09:00:11 pm
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> 
> What I'd really like to see is "disklatency" 
> output obtained on a fast EIDE system.
> 
Here are some latency results from my machine (2 runs):
P5-166, 40MBytes of memory.  I would not judge the
performance of SCSI in general too harshly, the Hawk
is not an extremely high performance drive.  I'll follow
up with some results from other systems that I can
test on later today.

NCR-SCSI driver ASUS SC200 W/ST12400 2.1GB Hawk
Command overhead is 1370 usec (time_4096 = 2093, time_8192 = 2815)
transfer speed is 5.6707e+06 bytes/sec
Command overhead is 839 usec (time_4096 = 2093, time_8192 = 3347)
transfer speed is 3.26577e+06 bytes/sec

Standard IDE W/WDC540H
Command overhead is 436 usec (time_4096 = 2001, time_8192 = 3565)
transfer speed is 2.61859e+06 bytes/sec
Command overhead is 436 usec (time_4096 = 2002, time_8192 = 3568)
transfer speed is 2.61586e+06 bytes/sec

EIDE W/WDC540H
Command overhead is 375 usec (time_4096 = 814, time_8192 = 1254)
transfer speed is 9.31994e+06 bytes/sec
Command overhead is 368 usec (time_4096 = 800, time_8192 = 1231)
transfer speed is 9.49095e+06 bytes/sec

EIDE W/WDC 1.6GB
Command overhead is 217 usec (time_4096 = 513, time_8192 = 809)
transfer speed is 1.38444e+07 bytes/sec
Command overhead is 196 usec (time_4096 = 502, time_8192 = 808)
transfer speed is 1.33987e+07 bytes/sec

SCSI 2.2X CDROM
Command overhead is 5655 usec (time_4096 = 9033, time_8192 = 12410)
transfer speed is 1.21281e+06 bytes/sec
Command overhead is 5670 usec (time_4096 = 9046, time_8192 = 12422)
transfer speed is 1.21324e+06 bytes/sec

John