Xref: utzoo comp.unix.questions:11055 comp.os.vms:11091
Path: utzoo!attcan!uunet!steinmetz!davidsen
From: davidsen@steinmetz.ge.com (William E. Davidsen Jr)
Newsgroups: comp.unix.questions,comp.os.vms
Subject: Re: Do OS's slow down with age?  (was: DDJ article / UNIX vs BS/2)
Message-ID: <12938@steinmetz.ge.com>
Date: 12 Jan 89 14:53:58 GMT
References: <209@imspw6.UUCP> <12872@steinmetz.ge.com> <370@siswat.UUCP> <1472@cps3xx.UUCP>
Reply-To: davidsen@crdos1.UUCP (bill davidsen)
Organization: General Electric CRD, Schenectady, NY
Lines: 45

In article <1472@cps3xx.UUCP> rang@cpswh.cps.msu.edu (Anton Rang) writes:

|   There is a lot of process creation overhead in VMS.  On the other
| hand, you don't need to create a process every time you do anything
| (as UNIX does).  In fact, most "basic" users (edit/compile/link) will
| log in and use only their one process (or maybe two, if they have a
| background editing process).

  I talked to a few VAX support people again, and they agree about
process creation. Unfortunately VMS does what's called "image
activation" which still results in reading a program from disk,
establishing an environment (in the VMS sense) and all the things UNIX
calls a subprocess, except accounting. This happens when you start the
editor, compiler, linker, run the program, etc. It still isn't cheap in
terms of system resources.

|   The file I/O overhead is significantly more than UNIX's if you're
| working with only sequential files--in particular, sequential text
| files.  Against this, balance the capabilities of indexed files.  If
| you have an application working with large indexed files, VMS gives
| you much more flexibility than UNIX (which hasn't even GOT indexed
| files, and won't let you control disk allocation if you want to make
| them up yourself).

  Do you have figures proving that VMS ISP is faster than database
access using hash or B+tree methods in UNIX? I don't have any figures,
but programs running in both environments seem to take about the same
real time per transaction on an unloaded system.

  I certainly never found the need for having the user control disk
allocation. I have always felt that fancy stuff should be in the
programs using them, not in the O/S. With SysV shared libraries there is
not penalty for having the library included in each program, a concept
which is known as "shared global libraries" in VMS.

  I still see no reason to think that non-portable operating systems are
inherently faster or smaller than UNIX. They *can* provide many more
features which may be useful to some applications, and which are useful,
if for no other reason than to lock applications to that vendor.

  Note that DEC is not using VMS on their new RISC machine. 
-- 
	bill davidsen		(wedu@ge-crd.arpa)
  {uunet | philabs}!steinmetz!crdos1!davidsen
"Stupidity, like virtue, is its own reward" -me