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From: jlg@lanl.ARPA (Jim Giles)
Newsgroups: net.arch
Subject: Re: paging and loading
Message-ID: <7961@lanl.ARPA>
Date: Thu, 25-Sep-86 13:53:58 EDT
Article-I.D.: lanl.7961
Posted: Thu Sep 25 13:53:58 1986
Date-Received: Fri, 26-Sep-86 00:57:00 EDT
References: <832@hou2b.UUCP> <7597@lanl.ARPA> <78@alberta.UUCP>
Reply-To: jlg@a.UUCP (Jim Giles)
Organization: Los Alamos National Laboratory
Lines: 23

In article <78@alberta.UUCP> cdshaw@pembina.UUCP (Chris Shaw) writes:
>People who are saying "the 205 runs programs x, y, and z faster without VM than
>with VM" are looking at only one job at a time. This is fine if your 205 does
>ONLY 1 thing all day, every day. Most machines run a mix of jobs, however,
>and in this much larger context, individual program performance is far less
>important than overall throughput. Anyone who was around in the days of
>"batch only" knows this argument inside and out. Batch is fine if you want
>to maximize individual program performance, but overall turnaround time is 
>dreadful, since ALL things sit in the queue, including the 1/2 second
>practice runs.

There are places where you really want to maximize individual program
performance.  Take global weather modelling for example: these people have
one big program (that must produce results faster than real time or the
result in not very interesting).  Other programs running in the system
at the same time are incidental - or even counter-productive.  Yes, there
is a trade-off between throughput and individual program speed.  My point
is that some applications don't care a bit about throughput - the machine
was purchased for the purpose of running one particular program as fast
as possible.

J. Giles
Los Alamos