Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!mephisto!prism!fsu!stat!mccalpin
From: mccalpin@stat.fsu.edu (John Mccalpin)
Newsgroups: comp.arch
Subject: Re: The Killer Micro From Hell
Keywords: cpu starvation, memory bandwidth
Message-ID: <787@stat.fsu.edu>
Date: 29 Dec 89 16:29:25 GMT
References: <158@csinc.UUCP>
Reply-To: mccalpin@stat.fsu.edu (John Mccalpin)
Organization: Supercomputer Computations Research Institute
Lines: 37

In article <158@csinc.UUCP> rpeglar@csinc.UUCP (Rob Peglar x615) writes:
>
>Anyway, you should carefully look at the issue of CPU starvation on some
>of the very machines you tout - like the Cray-2.  Some (not all) of the
>smaller machines exhibit much less CPU starvation.  The ETA-10 is (was)
>another notable example of real and potential CPU starvation as an
>architectural flaw.

It seems odd to mention the Cray-2 and the ETA-10 in the same sentence
with regard to "CPU starvation".  It seems to me that the ETA-10 is a
much more balanced design with regard to memory bandwidth -- I don't
know about I/O speeds past the shared memory, though...  With the most
recent release of the operating system, we have gotten paging rates of
>500 MB/s on thrashing jobs.  This is almost 1/2 of the physical I/O
bandwidth to shared memory.  Earlier system software certainly left the
cpu hungry, but the hardware is capable of some pretty tremendous
bandwidth, and the software is finally starting to catch up....

>There will always be room for big supers.  The room, however, is becoming
>smaller.  Don't get squeezed.

When Cray Research was founded, they estimated a world market for
supercomputers that was in the neighborhood of 40 units.  Maybe they
weren't so far off after all!

Anyway, here at FSU we have been pushing the KILLER MICRO bandwagon,
too.  Lets get all those !@#$%^&* scalar jobs _off_ of our vector
machines and onto the killer micros where they belong....  Then those
of us who can effectively use the vector machines will have more time
available.

By the way, I estimate the the (soon-to-be-installed) FSU Cray
Y/MP-4/432 will only be about 125 times as fast as the new MIPS "KILLER
MICRO from HELL" on my code.  Yep, they are closing the gap all right....

>Rob Peglar	Control Systems, Inc.	2675 Patton Rd., St. Paul MN 55113
>...uunet!csinc!rpeglar		612-631-7800