Re: real kernel bloat

Matti E Aarnio (mea@mea.cc.utu.fi)
Thu, 27 Jun 1996 12:09:30 +0300 (EET DST)


Alex Krimkevich <alex@magneton-ra.swmed.edu> writes:
> Alan Cox writes:
> > > almost anything. It is true that DEC's kernel is several Megs in size,
> > > but don't forget it is capable of much more than Linux is, and,
> > > arguably, will ever be. The lacking capabilities are of no concern
> > > to most people, however the truth remains: Digital UNIX is a better
> > > multitasking, multiuser OS than Linux. I am no DEC's or Sun's fan,
> >
> > On what measurements. which facilities, what hardware size.
>
> Well, my personal experience has been, that Linux' performance
> deteriorates pretty rapidly as the load increases (be it one user
> running more jobs or more users being logged in). You, probably,
> know, that Digital Unix 4.0 is capable of supporting 4000 users
> (so they claim). It has got fail over features (clustering), it
> scales to more processors than Linux does, it's got logical
> volume manager, journaling file system, and the list goes on
> and on. And it knew how to do those things 5 years ago.

Naeh, you are giving too much credit to DEC -- they did not
do ALL of that 5 years ago :-) One of the lattest additions
is true clustering to UNIX machines.

We (changeing 'hats' -- ftp.funet.fi hat on) use DEC hardware
at the server, and it is preforming pretty well. If we decide
to put enough money, we could upgrade the old single-CPU "Super
Workstation" ( DEC 3000/900 ) to something with multi-gigabyte
memory, and multiple processors. (Now we hit CPU load limit
while filling our multiple 34 Mbps links -- multiple inside
Finland, plus one abroad..)

One of the reasons to chose DEC instead of SUN about two years
ago was DEC AdvFS, their journalled+multi-spindle+... fs. Also
we liked DECs StorageWorks concept, and their RAID controllers.
(Old system had just non-fault-tolerant RAID-0 (spanning) of
multiple disks into one larger volume, and when any of the
component disks did fail, whole volume did fail. With dozens
of disks it did happen way too often... )

Naturally we had some initial difficulties with the then new system,
but we got good support from DECs technical staff (Finland), and all
kinks have long since been ironed out -- odd that SUNET people did
tell to us that they did get very poor support from DEC Sweden,
they changed from DEC to Sun recently.

Having somebody to whom to yell at when things don't work with the
big system is always comforting.. (If one must look at the mirror
to find the best service contact, the thing is occasionally tiresome..
Sure, there are things I would any day put at Linux platform, but
there are also things I would not do -- yet.)

.. reminds me; Linus asked me when 2.0.0 was released approx:
"When will you install Linux at ftp.funet.fi ?" I answered
something about "Well, we need something new: Log-based filesystems,
and improvements at various other areas..."
(You don't do 100+ GB data storages at raw EXT2 or any other
such system! With or without RAID below your FS.)
...
> >The place stuff like OSF/1 should still win is going to 12
> > processor .5Gb Alpha's. The really big stuff, and thats primarily because we
> > don't have any of those handy for a Linux port and to do all the tuning.
>
> That's precisely what they are after. It appears to me, that neither
> Sun nor Dec are after mass market. They are keeping to themselves
> the workstation users by spewing out a better hardware every once
> in a while, and trying to expand in their "really big" stuff.

Yes, selling costly ("expensive" is reserved for CRAYs et.al.
special systems in my vocabulary..) systems to customers with
good profits is always better, than selling bulk/commodity stuff
with marginal profits.

...on the other hand, see what selling bulk got Microsoft to be...
:-) Everybody thrives with the "killer applications", first one
ever was called VisiCalc, does anybody remember ? (Or are you
so young ? No comments at that, please. It was the first spread-
sheet program.)
...
> Let me sum things up: Linux has not conquered the world yet,
> but keep up a great job, guys.

Yes we do :)

> Alex Krimkevich.
>
> P.S. I just wanted to re-instill the sense of reality on this
> mailing list :-)

Indeed, lets have some talk about journalled filesystems.
Are there experts who could do a generic journaling layer
which could be injected to any of the filesystems ?
(FYI: Sun does have such at Solaris 2.5.)

/Matti Aarnio <mea@utu.fi> <mea@nic.funet.fi>