Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!samsung!uakari.primate.wisc.edu!unmvax!ariel.unm.edu!nmsu!opus!pfeiffer
From: pfeiffer@nmsu.edu (Joe Pfeiffer)
Newsgroups: comp.benchmarks
Subject: Measuring disk read times for Unix
Message-ID: <714@opus.NMSU.Edu>
Date: 27 Feb 91 16:41:00 GMT
Sender: news@NMSU.Edu
Distribution: comp
Organization: NMSU Computer Science
Lines: 16

I have a need to measure transfer rates and system time required for
disk reads and writes under Unix, for modelling purposes.  The data
must be paramaterized by block size.

In order to measure write times, I'm using the O_SYNC to flush my data
to disk on each write.  So far so good.

I'm having trouble trying to do the equivalent for reads.  I appear to
be filling up the OS's disk buffers on the first pass through the
test, after which reads come from there.  While an obvious solution of
making the test file so huge it won't all fit in there would help, it
wouldn't be a complete solution.

Any thoughts?

-Joe.