*BSD News Article 86309


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From: Patrick Gainer <gainer@64k.com>
Newsgroups: comp.unix.bsd.freebsd.misc,comp.arch,comp.benchmarks,comp.sys.super
Subject: Re: benchmarking discussion at Usenix?
Date: Thu, 09 Jan 1997 09:33:37 -0800
Organization: 64K, Inc.
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Hugh LaMaster wrote: 
> Larry McVoy wrote:
> >         . osbench
> >                 - Steve Kleiman suggested that I (or someone) grab a big hunk
> >                  of OS code and port it to userland and call it osbench.  This
> >                  is an interesting idea.
> 
> An interesting idea.  Various papers over the years (e.g. Alan J. Smith
> at U.C. Berkeley?) have noted that when real hardware is instrumented,
> operating systems tend to have much higher cache miss rates than
> predicted by applications.  By porting an application to user-land,
> hopefully at least that much of OS behavior could be captured.  [There
> are obviously a lot of difficult-to-simulate OS activities as well...]

Now I know this may not be of general applicability but for those who
are
interested, you can profile the kernel today on SGI Challenge machines
running
with an R10000 processor. The on-chip counters may be accessed from user
applications and may be configured to monitor only user events, only
kernel
events, or both. The types of events one can monitor with the R10000 are
pretty
numerous and some really good data may be collected.

Having done some comparisons of different types of workloads, monitoring
all
sorts of things from types of cache misses to CPI values it is very
reasonable
to assume the kernel has higher cache miss rates and lower IPC values
than 
user applications (including relational database workloads - which are
pretty 
bad in their own right).
 
> >         . freespec
> >                 - I'm unhappy about the current spec.  I'd like to build a
> >                   freeSpec97 that is similar to spec (uses the same tests)
> >                   but has lmbench style reporting rules (cc -O/f77 -O) and
> >                   is free of any charges.  Any interest?
> 
> Great idea.

Yep, this is the best suggestion of the lot. It's not been uncommon for
certain
folks to criticize lmbench by saying some of the things it measured
weren't 
that relevant at times. Adding a freespec would be a wonderful addition.

Pat