[rescue] This Just In: HP to buy Compaq

[David Passmore]

On Wed, Sep 05, 2001 at 04:42:15PM +0100, Paul Sladen wrote:

>   a)  The kernel, scalable enough to run on your Palm Pilot, and your S/390.
>       Please don't bring up the issue of efficeny;  Solaris doesn't run on
>       a Palm, and NetBSD (a Real-Unix(TM) that does) doesn't `scale' to SMP.

Disclaimer: I run Linux on the x86 box I use for my main development
machine, primarily because of the speed in which the Athlon compiles; I
don't run FreeBSD or some other variant simply because I'm familiar enough
with Linux and it works for what I use it for. This message is meant to
convey my knowledge and opinion of Linux and other systems from my point of
view as a programmer and systems architect.

Linux has definitely risen to prominence in the server arena before its
time. The media hype machine has latched onto it as an alternative to
Microsoft and propelled it to heights it is not ready for, and may never be.
Combined with the sometimes fanatic devotion you see to it, it's easy to
believe for an end-user that Linux is the end-all be-all of operating
systems.

Sun has spent a considerable amount of time and effort trying to make
Solaris scale vertically on multiprocessor machines. As of Solaris 8, there
are no places in the kernel at which it can block in a system call; in Linux
2.4, there are over two thousand. With an emphasis on adding code to support
more platforms and devices, this is going to get worse before it gets
better. It's a Herculean task, really, to retrofit a kernel that wasn't
designed this way from the ground up. If you have ever looked at the Linux
kernel source, it is spaghetti, with no emphasis on a common coding style,
architecture, or in-line documentation convention; this will just make the
task worse.

I/O to multiple devices under Linux takes place using a single lock,
defeating much of the purpose of parallelizing I/O... to multiple devices.
Yes, in Linux only one I/O can be scheduled at a time.

Kernel-space threading for user processes is still immature and difficult to
use; ask any developer who has tried to port a major multi-threaded
application from Solaris to Linux, and his eyes will turn blood-red and
smoke will pour from his mouth. The semaphore implementation has much to be
desired. 

Linux doesn't support true asynchronous I/O, not even the POSIX
implementation.

Many Linux 'fans' over the years have touted the speed of the ext2
filesystem versus ones like FFS or UFS. ext2 gets its speed because it
performs asynchronous writes and NO CONSISTENCY CHECKING except at fsck
time. With the inclusion of XFS, this situation is getting better.

Because it was designed for 'low-end' Intel hardware, Linux suffers from
many workarounds; for instance, 'bounce buffers' to address memory over a 32
bit boundary. Yes, Linux actually has to /copy/ data which resides in memory
over 2GB underneath that boundary to address it. This *KILLS* performance on
high-end systems.

And so on, and so forth... while many of these points are well-known and the
kernel is getting better, the simple fact of the matter is that Linux is
still not ready for many enterprise uses, and shouldn't be pushed for such.
I have my doubts as to whether Linux will eventually get to the scalability
point that systems like Solaris or IRIX are at, simply because that kind of
work is not sexy or fun, and is the stuff serious computer scientists (yes,
I mean scientists) are made of.

But, yes, Linux will indeed run fine on your Palm Pilot (tm).

As for the GPL; I use many fine GNU utilities every day. But please, as a
programmer, don't push the GPL on me. That's not freedom. It's my right to
release my software under any license I please. I am annoyed enough by this
movement to actively purge any need for GPL code from whatever I may be
writing, no matter what the cost in duplication of effort. In my estimation,
the virus-like attachment of GPL code (even in a seperate library) to
whatever code uses it, no matter what the license, is not freedom. It's
enslavement. Again, that is just my opinion.

David