Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!husc6!bu-cs!madd
From: madd@bu-cs.BU.EDU (Jim Frost)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Why unix doesn't catch on
Message-ID: <31084@bu-cs.BU.EDU>
Date: 13 May 89 16:30:12 GMT
References: <7632@phoenix.Princeton.EDU> <256@jwt.UUCP> <2496@bucsb.UUCP> <274@tree.UUCP> <13723@steinmetz.ge.com> <13630@ncoast.ORG>
Reply-To: madd@bu-it.bu.edu (Jim Frost)
Followup-To: comp.sys.ibm.pc
Organization: Software Tool & Die
Lines: 29

In article <13630@ncoast.ORG> mikes@ncoast.ORG (Mike Squires) writes:
|The UNIX file
|system also seems faster than PC-DOS.

UNIX does caching by default; this alone can make the apparent speed
of the filesystem greater.  Newer UNIX filesystems (BSD FFS and
Silicon Graphics' EFS are two examples) also try to put data where it
will be easier (read: faster) to get, with good success.

MS-DOS does (some) write-through caching which slows things
considerably on disk writes.  With the right drivers you can give it
"real" caching which I found tended to speed things up anywhere from
20% to well into the hundreds (I had 4Mb of cache, though).  I have
yet to see any extension to MS-DOS which tries to optimize data
placement, with the exception of disk reorganizers which tend to
optimize for fragmentation and not for organization within cylinders,
etc.

It's difficult to benchmark UNIX versus MS-DOS because most of the
benchmark programs are designed to test pure performance (eg how fast
you can write 20 megabytes or calculate pi to two million digits)
instead of testing average conditions, which is a much fairer and more
informative test.  Since the "average" UNIX load is usually ten to
twenty system processes and several users (each with two or more
processes), and the "average" MS-DOS load is one application, it's
pretty hard to come up with a comparison.

jim frost
madd@bu-it.bu.edu