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Path: utzoo!utgpu!water!watnot!watmath!clyde!rutgers!lll-lcc!pyramid!prls!mips!hansen
From: hansen@mips.UUCP
Newsgroups: comp.arch
Subject: Re: Word vs. Byte Orientation
Message-ID: <298@dumbo.mips.UUCP>
Date: Tue, 14-Apr-87 18:40:10 EST
Article-I.D.: dumbo.298
Posted: Tue Apr 14 18:40:10 1987
Date-Received: Thu, 16-Apr-87 01:01:31 EST
References: <16122@amdcad.AMD.COM> <16126@amdcad.AMD.COM>
Lines: 42
Summary: MIPS does kernel simulations too

In article <16126@amdcad.AMD.COM>, tim@amdcad.AMD.COM (Tim Olson) writes:
> In article <16122@amdcad.AMD.COM>, bcase@amdcad.AMD.COM (Brian Case) writes:
> > In article <279@winchester.mips.UUCP> mash@winchester.UUCP (John Mashey) writes:
> > >Thus, we have really precise statistics on what's going on, at least on
> > >our machines, at the user-level, for anything form typical UNIX programs
> > >(like nroff), to large simulators [spice, espresso],
> > >parts of the compiler system [assembler, optimizer, debugger],
> > >to benchmarks like whetstone, dhrystone, linpack.

> > Sigh, I wish we could do such simulations.

> I think Brian misread the previous paragraph to mean that the MIPS simulator
> is able to run these programs in a simulated UNIX environment (i.e.
> simulating the entire UNIX kernel), but I see only user-level mentioned, above.
> Note that we *are* able to perform such simulations, but only in a single-
> tasking, stand-alone environment.

> John -- does the MIPS simulator incorporate a simulated UNIX kernel, and have
> you performed multiprogramming simulations with it?

Yes - for example, we've run the Byte multi-shell benchmark on our simulator.

Actually, we have several MIPS simulators, and in addition to the user-level
simulations, we've been running kernel-level simulations as well.  The
kernel-level simulations take just a little longer, since we use an
instruction-level simulator to generate the address trace.  (The user-level
simulations generate the address trace by an object-code recompilation
technique that is also employed by our profiler.  As a side note, by using
this technique, we can simulate and/or profile any MIPS object code, without
having separate profiling libraries.)

The user-level simulations take into account the effects of multiprogramming
and kernel code execution in simple ways. We have found that our simulations
have matched within better than 5% to the actual run-time as reported by
the csh time command on our M-series systems. Now that we've got all our
MIPS systems connected by NFS, I've been able to run plenty of simulations.

-- 
Craig Hansen
Manager, Architecture Development
MIPS Computer Systems, Inc.
...decwrl!mips!hansen