*BSD News Article 49667


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Newsgroups: comp.periphs.scsi,comp.os.linux.hardware,comp.unix.bsd.freebsd.misc,comp.os.linux.setup
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From: dyson@inuxs.inh.att.com (John S. Dyson)
Subject: Re: SCSI PCI host adapter
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References: <418r3m$9c6@trauma.rn.com> <41sjek$rtu@bonnie.tcd-dresden.de> <1995Aug29.125909.28500@wavehh.hanse.de> <shimon.809740893@ark>
Date: Wed, 30 Aug 1995 14:59:53 GMT
Lines: 28
Xref: euryale.cc.adfa.oz.au comp.periphs.scsi:36167 comp.os.linux.hardware:14122 comp.unix.bsd.freebsd.misc:5024 comp.os.linux.setup:18034

In article <shimon.809740893@ark>, Simon Shapiro <shimon@ssd.intel.com> wrote:
>
>1.  Where does one find Bonnie?
>
>2.  Interesting that CPU utilization is 85-99%.  Does not leave much to other
>    things.
>
>3.  Where is the 8MB/Sec reported in this thread?  I saw 1.5 or so.
>
>Cheers, Simon
>
The 1.5MB/Sec is an artifact of the performance of the stdio library.  It
is normally insane to use getc/putc to copy large files (or to perform
massive file updates), but those figures are given to show the performance
of the character by character stdio routines.  The OS performance is the
higher block-by-block transfer rate.  The high CPU utilization numbers
are also an artifact of doing the silly (for performance reasons) character
by character I/O.  Note that the block I/O shows much lower CPU overhead.

To sum it up, the character-by-character I/O figures are more of a
user-space benchmark, and the block I/O is an OS (kernel) benchmark.

John
dyson@root.com