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From: booker@network.ucsd.edu (Booker bense)
Newsgroups: comp.unix.cray,comp.unix.large
Subject: Re: "vi" & Supercomputer Performance
Summary: Well we use it.
Keywords: performance, annecdote
Message-ID: <3814@network.ucsd.edu>
Date: 4 Oct 90 22:33:54 GMT
References: <1990Oct4.050509.11405@eagle.lerc.nasa.gov>
Followup-To: comp.unix.cray
Distribution: usa
Organization: San Diego Supercomputer Center @ UCSD
Lines: 42

In article <1990Oct4.050509.11405@eagle.lerc.nasa.gov> vvawh@convx1.lerc.nasa.gov (Tony Hackenberg) writes:
>Does anyone know of any studies on the effect of allowing
>vi usage by many users on supercomputer performance?
>
>Does anyone know if there are versions of "vi", "emacs", or other
>full screen editors that are written to minimize performance 
>hits on supercomputers?
>
>
>
>--

Several people in the systems group here have studied such things, they 
have even developed an rvi which allows remote editing of files on the 
YMP. My "limited" understanding of it is that is uses tcp/ip sockets to 
grab the file down to your workstation. The actual editing takes place
there and when you save the file , the changes go back to the YMP.

People to contact about this would be schroeder@sdsc.edu or
zhengc@sdsc.edu. 

In my experience the biggest effect of many small interactive jobs 
is that is makes getting any performance benefits out of auto-tasking 
very difficult. The more processes there are the more difficult it is
to get all of your processes into the cpu. I hear rumors that Unicos 6.0
will include the idea of a "family" of processes and schedule all of
them into the cpu at the same time.

Also editing( depending on how the scheduler works and how big your
ssd is ) can be a very frustrating task. Being swapped out for 40 secs
is not fun. One of the local modifications to the kernel we have made 
here is to include a second-swapper for interactive jobs. Another change
made was include a penalty for excessive system calls in the swapper.
As a general rule , if the system overhead gets much above 7-8% , everyone
feels the effects. 

- Booker C. Bense

/* benseb@grumpy.sdsc.edu
These are my own ramblings, no offical opinion , endorsement or actual 
fact is implied. 
*/