*BSD News Article 73204


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From: "John S. Dyson" <dyson@inuxs.att.com>
Newsgroups: comp.os.linux.networking,comp.unix.bsd.netbsd.misc,comp.unix.bsd.freebsd.misc
Subject: Re: TCP latency
Date: Tue, 09 Jul 1996 11:34:03 -0500
Organization: Lucent Technologies, Columbus, Ohio
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Larry McVoy wrote:

> 
> Usenix paper table for just FreeBSD vs Linux.  The stuff that was "unfair" is
> "Simple process" and "/bin/sh process".  I'm not really sure it is reasonable
> to call that "unfair".  It's just a different library style.  FreeBSD could
> have done the same thing.  The point of thebenchmark is to draw out these
> differences.
> 
Fairness is a term that is concocted by children.  However, the benchmarks
need to be done with all other things equal.  For example, the benchmarks
that were run A LONG time ago on an OLD, released version of FreeBSD are
hard to compare with a development version of Linux.  FreeBSD V2.1 is of
the same timeframe as Linux 1.2.13.  FreeBSD V2.2-current is of the
same timeframe as Linux 2.0.  FreeBSD V2.2-current is due for release in
a few months -- the FreeBSD V2.1-stable (old code) has taken up alot of
time, to support existing users who need the best stability...  Since
The FreeBSD V2.2 kernel is very stable right now, I would suggest comparing it to
Linux V2.0 (which is also a kernel.)

Generation wise: FreeBSD V2.2-current and Linux V2.0 are best to compare,
while FreeBSD V2.1-stable and Linux V1.2.12 are good to compare.

>                     L M B E N C H  1 . 0   S U M M A R Y
>                     ------------------------------------
> 
>             Processor, Processes - times in microseconds
>             --------------------------------------------
> Host                 OS  Mhz    Null    Null  Simple /bin/sh Mmap 2-proc 8-proc
>                              Syscall Process Process Process  lat  ctxsw  ctxsw
> --------- ------------- ---- ------- ------- ------- ------- ---- ------ ------
> i586.1    FreeBSD 2.1-S  133       9      3K     12K     20K  105     24     28
> i586.120   Linux 1.3.28  120       2      1K      5K     16K   69     10     13
>
  i586.166  FreeBSD 2.2-c  166             500uses  1.2K    7K   --     --     --

Of course, when you need fast perf, we don't suggest using shared libs, per
the numbers above.  Note that FreeBSD V2.2-current scales better than Linux
1.3.28 above?  Of course my comparison is just as bogus as the two previous.
I am just making a point that the benchmarks are only meaningful with critical
interpretation. (BTW, my numbers are correct -- but are only accurate for the
machine that I ran them on, under the conditions that I ran them under.)
 
Considering the static shared libs for Linux of that generation, the DIFFERENT
hardware used for the measurement, and the fact that some of the 2.0 enhancements
had already gone into 1.3.28 and FreeBSD V2.1 is a *conservative* release, these
numbers are only interesting to compare NEWER Linux with OLD FreeBSD on different
hardware :-(.

The shell thing is interesting also, because the lmbench benchmarks don't show
a big (if any) difference between the FreeBSD shell and BASH when running
on FreeBSD-current :-).  In fact, I run with bash exclusively, because it
doesn't hurt on FreeBSD at all anymore, when there is enough memory.
FreeBSD-current handles large programs very efficiently, faulting them in
approx 3X faster than Linux V2.0 (both reading and soft pagefaults.)  I did not
mean to create a red-herring about the shell.

John