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Date:      Mon, 1 Apr 1996 21:03:28 +0930 (CST)
From:      Michael Smith <msmith@atrad.adelaide.edu.au>
To:        dutchman@spase.nl (Kees Jan Koster)
Cc:        freebsd-hackers@FreeBSD.org
Subject:   Re: HDD cpu usage (IDE vs. SCSI).
Message-ID:  <199604011133.VAA06543@genesis.atrad.adelaide.edu.au>
In-Reply-To: <199604010903.LAA07931@deimos.spase.nl> from "Kees Jan Koster" at Apr 1, 96 11:03:46 am

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Kees Jan Koster stands accused of saying:
> 
> I was told that cpu usage of SCSI disks was lower than that of IDE disks.

... in general, it is.

> LikeEver (amd486DX4-100, ncr pci scsi controller)
> Seagate    -------Sequential Output-------- ---Sequential Input-- --Random
>            -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks
> Directory  K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
> /usr        1299 81.1  1263 15.5   653 18.2  1778 94.9  1982 41.8  47.7  5.7
> /tmp (mfs)   689 33.7   285  3.4   274  4.5   397 17.5   503  5.7  27.0  3.3
> 
> Maxtor     -------Sequential Output-------- ---Sequential Input-- --Random
>            -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks
> Directory  K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
> /var         750 41.9   740  8.5   405  9.7   764 34.7   770  8.8  32.0  3.9
> /tmp (mfs)   948 48.5   479  6.4   481  9.3   772 39.0  1228 19.3  39.0  4.7
> /msdos        28  4.5    74  3.3    43  1.9   111  7.7   111  3.6   9.6 10.9
> 
> phobos (pentium 90, on-board IDE controller)
> Quantum    -------Sequential Output-------- ---Sequential Input-- --Random--
>            -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
> Directory  K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
> /usr        1215 41.7  1818 18.8   811 11.5  1376 41.0  1990 16.0  39.9  3.9
> 
> How come the seagate uses twice as much cpu as the quantum?

Try comparing apples with apples.  Your benchmarks are pretty meaningless,
but one obvious observation : P90's are faster then DX4's.

> Kees Jan Koster                   e-mail: dutchman@spase.nl

-- 
]] Mike Smith, Software Engineer        msmith@atrad.adelaide.edu.au    [[
]] Genesis Software                     genesis@atrad.adelaide.edu.au   [[
]] High-speed data acquisition and      (GSM mobile) 0411-222-496       [[
]] realtime instrument control          (ph/fax)  +61-8-267-3039        [[
]] Collector of old Unix hardware.      "Where are your PEZ?" The Tick  [[



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