From: hedrick@geneva.rutgers.edu (Charles Hedrick) Subject: Re: linux a real unix? Date: 25 Apr 1993 17:32:27 GMT
sgberg@charon.bloomington.in.us (Stefan G. Berg) writes:
>I was just wondering how linux compares to the commercial Unix systems
>you find in Sun's, HP's, etc... Reading all these postings about "ported
>blabla to linux", it seems that linux does not yet do too good in terms
>of compatibility. And how about in terms of efficiency? Seems that linux
>runs in very little memory, so it does seem to be more memory efficient
>than those commercial unix's, but how about speed?
At this point I think Linux is about as "compatible" as most of the
commercial Unices. Porting depends upon the nature of the package.
For simple software that sticks to ANSI C, you may not have to do
anything. For more complex things, typically there's a configuration
file or header file that defines the combination of features
appropriate for each variant of Unix. So if nobody has built it for
Linux yet, you've got to set that up. At this point Linux has a
fairly good libc. The primary problems at the moment are in areas
outside what I'd call the central core of Unix features: shared
memory, IPC, etc. There's code for System V versions of that, but
based on postings here it's not clear how stable it is.
The few benchmarks that have been posted suggest that basic Unix
facilities, e.g. fork and exec, are comparatively fast under Linux.
I/O is going to depend upon which type of controller you use and which
file system. There are a few commercial versions of Unix designed for
use in server environments. They have been tuned to support multiple
processors, intelligent disk controllers, etc. Linux can't provide
competition in that area. For a typical system with an IDE disk, I
think it does fine, and it sounds like with certain SCSI controllers
it's OK as well (but I'm not up to date on SCSI support).
I have a 486/33 with one IDE disk and a generic ET4000 SVGA
controller. Until recently I had a Sun IPC on my desk at Rutgers,
with two SCSI disks. I found that the overall "feel" was fairly
similar. Certainly text scrolling in xterm was faster on the Sun
(because it has hardware bitblt, and the ET4000 doesn't). Presumably
use of an intelligent SVGA card (e.g. S3) would fix that. (I have
compared detailed X benchmarks. The ET4000 actually does pretty well
against the IPC until you get to things that involve working with
areas. That's where intelligent display hardware helps. For my
normal usage -- which is primarily with text -- scrolling is the main
place where I see a difference. I have to say that I find the slow
scrolling with an ET4000 annoying.) I also have the feeling that
doing a compile in one window has a bit less impact on response in
other windows on the Sun. This would make me suspicious of what would
happen if you put a lot of people on a Linux system. The SLS
distribution seems to include most of the standard free software that
we make available to people on our Suns. But we've spent a fair
amount of time collecting that software and setting it up for
distribution on campus. A full SLS distribution would make a lot more
interesting system than a Sun as it comes "out of the box". (In case
you wonder about the past tense -- currently I have a SparcClassic.
It is noticably faster than a 486/33, which should not be surprising
given some basic information about the processors. It's possible that
a 486/66 would be comparable.)
I have to say that my experience with commercial Unix on Intel has not
been encouraging. I had Microport SVr2 on a 286 for a couple of
years. Linux is infinitely better, in features, reliability, and
support. I've also used ATT's SVr4, but not enough that I want to
comment on it in detail. Note that I haven't used any of the high-end
Unix ports, e.g. SCO, Destiny, or Solaris. They would be more likely
to have advantages over Linux for commercial users, though not
necessarily for most of the current Linux user base.
I think it's important not to oversell Linux, or people may be
disappointed. I think it's a great system for home use, both for
faculty and students. It has most of the the Unix software I use on
Suns at Rutgers, and it performs very well. I know there are places
that use it for commercial work successfully. I think if I had a
small company and wanted to support somebody on the console and a
couple of terminals, and I was developing my own software (i.e. I
didn't need commercial database packages, etc.) I might consider it.
But it's not the system I'd choose to support 50 timesharing users (we
do have Suns used that way), nor is it one I'd use for our
university-wide administrative database system. I don't see any
reason to be apologetic about its capabilities. It does just as well
as a delivery vehicle for software from the university/research
community as commercial Unices do as delivery vehicles for commercial
applications. Not everybody in the world wants to run TeX, Common
Lisp, Interviews, etc. But enough do to provide a continuing place
for Linux or similar systems.