Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!voder!pyramid!ctnews!mitisft!dold
From: dold@mitisft.Convergent.COM (Clarence Dold)
Newsgroups: comp.periphs
Subject: Re: Hard drive speeds
Message-ID: <1202@mitisft.Convergent.COM>
Date: 28 Aug 89 18:19:04 GMT
References: <13700@brunix.UUCP>
Distribution: na
Organization: Convergent Technologies, San Jose, CA
Lines: 32

in article <13700@brunix.UUCP>, sgf@brunix (Sam Fulcomer) says:

> In the modern Unixes which I know about processes are born with a swap. Other
> swapping (during normal scheduling) depends on the implementation of the
> scheduler, but they (as far as I know) all do it. 

> Try running this shell script, called fubar, on your machine and tell me if
> it swaps:

I didn't try the shell script, but I wonder if it's swapping that kills
your system.  The Bourne and Korn Shells both use tmpfile(3s) to create,
and immediately delete, a scratch file, probably in /usr/tmp.
Althought the file doesn't appear in an 'ls', since it's already deleted,
you can see its former name with 'hd /usr/tmp'.
A short shell script beats on this file system.
Try a sh script:
i=0
while :
do
	i=`expr $i +1`
	echo $i
done
Not only is it slow as all get out, but the disk thrashes.
sar -r ( a swap monitor on our UNIX ), shows no swapping.

We don't swap to start processes anymore.
Even if we did, the shell would already be there, and not cause a swap.

Convergent/Unisys is primarily System V.
-- 
Clarence A Dold - dold@tsmiti.Convergent.COM
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