*BSD News Article 92076


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From: Tony Griffiths <tonyg@OntheNet.com.au>
Newsgroups: comp.unix.sco.misc,comp.unix.bsd.freebsd.misc,comp.unix.bsd.bsdi.misc,comp.sys.sgi.misc
Subject: Re: no such thing as a "general user community"
Date: Fri, 28 Mar 1997 12:10:25 +1000
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J Wunsch wrote:
> 
> I had to give a training course about DEC Unix system administration
> lately.  DEC Unix wasn't a bad experience, i have to admit, in
> particular if someone comes from a BSD background.  It has a very
> consistent documentation, i basically learnt the admin tasks within a
> couple of days.  And they even have implemented some neat BSD features
> like ``ps alx'', including the VSZ vs. RSS figures that are sorely
> missing in the SysV ps command once you know about them.

From my experience of working in the (Wide Area) Networks Engineering
group,
I would say that FreeBSD is between Ultrix [4.3 BSD] and DEC Unix
[OSF/1] in
look and feel.  Most of the utilities have the same switches which is
goodness when compared with the operation of Solaris which is the other
Unix I have to deal with!

> 
> Anyway, i noticed that from a cursory view, most of the smaller
> processes have been ranging at a VSZ of 1 MB ... 2 MB.  Almost none of
> them were below 1 MB.  Now compare this to a typical FreeBSD ps output
> you have in mind, and you'll quickly notice that this is about two or
> even three times larger on DEC Unix, roughly.

In fact, the binaries are on average about 2.25 - 2.5 times larger on
Alpha
then the equivalent VAX/i86 CISC binaries.  The lack of byte and short
memory
addressing appears to be the cause of much of this bloat.  These
instructions
have been added to the latest Alpha chips (EV56 and EV6) but it will be
some
time before they have an impact due to backward compatibility problems!

> 
> This is nothing surprising, if you know that a RISC CPU needs two CPU
> instructions in order to load a single address, and that all addresses

Not entirely true if you are accessing 32 or 64-bit naturally aligned
data
which requires only one instruction.  Anything else requires 2 to 11
instructions from (my) memory...

> are 64-bit there, that you have more wasted space by padding etc.  But
> it simply shows that the memory requirements of the same task on an
> Alpha CPU are very likely to be higher than they were on a 32-bit CISC
> CPU.

Instruction bloat is one thing that has an impact on main memory (and
cache and
TLB and ...) requirements.  Obviously, a 32-bit int or 64-bit long is
the same
on any architecture and occupies the same amount of memory so as the
data
areas of a program get bigger, the relative advantage of smaller a code
section
decreases.

> 
> --
> J"org Wunsch                                           Unix support engineer
> joerg_wunsch@interface-business.de       http://www.interface-business.de/~j

Tony