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From: malcolm@ee.UUCP
Newsgroups: net.unix
Subject: Re: Speed of read vs. fread
Message-ID: <67400002@ee.UUCP>
Date: Mon, 21-Jan-85 19:59:00 EST
Article-I.D.: ee.67400002
Posted: Mon Jan 21 19:59:00 1985
Date-Received: Wed, 23-Jan-85 05:07:17 EST
References: <626@ihlts.UUCP>
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Nf-ID: #R:ihlts:-62600:ee:67400002:000:940
Nf-From: ee!malcolm    Jan 21 19:59:00 1985


	/* Written  9:36 pm  Jan 19, 1985 by lied@ihlts in ee:net.unix */
	Which is faster, read/write or fread/fwrite?
Depends on what you are doing.  If you are doing single character IO then
by all means use fread/fwrite.  The time it takes to put the character in 
the buffer is insignificant to the expense of a syscall.

On the other hand large chunks of IO (several BUFSIZ's at a time) are much
more efficient with read/write.  One of my research programs saved many
seconds of CPU time by using write() to output large matrices (100k bytes)
for debugging.

The question is where to draw the line.  I would recomend that in general
to use fread/fwrite.  If you are reading/writing more than 5 or 10k at a
time (one call to read/write) then you'll start saving a little time by
using read/write.

					Charter member of the Purdue
					team to stamp out unnecessary
					sys-calls.

					Malcolm
					pur-ee!malcolm
					malcolm@purdue.arpa