Subject: Re: Linux seeming to run faster?
To: Matthew Orgass <>
From: Greg Lehey <>
List: tech-kern
Date: 10/10/2000 18:26:08
On Sunday,  8 October 2000 at  3:22:10 -0400, Matthew Orgass wrote:
> On Sat, 7 Oct 2000, Greywolf wrote:
>> I have a question that's been kind of burning on me for a while now,
>> and that is what in blazes are they doing that is giving the illusion
>> that they run faster than we do on just about every platform?
>   Linux probably does run faster on every platform.  Just try to read the
> source to see why:  most of the OS is MD and must be rewritten for each
> port.  In many places, Linux directly uses MD instructions where NetBSD
> has several function calls.  In other places, Linux structures represent
> registers where NetBSD structures represent whatever the registers mean.
> Porting Linux almost means writing a new OS.
>   In return, the time it takes to port NetBSD is a small fraction of the
> time it takes to port Linux, and once that is done one hour of MI work on
> NetBSD is usually worth at least 1 * N ports hours work on Linux and often
> much more.  There are far more Linux developers than NetBSD developers,
> yet NetBSD runs better on more platforms.

I think you're missing something here: the speed of the OS is not just
in the low-level code.  Sure, you can file a few instructions here or
there by writing things MD, but the real issue is in more complicated
structures like the VM system.

>> Tried Linux.  Want NetBSD.  But what gives in the performance
>> department?
>   You shouldn't see a huge performance difference unless something is
> wrong. A 5% difference on modern hardware would be reasonable (with some
> time made up by better algorithms).

I think before you get too concerned, you should measure the
performance.  There's been a lot of FUD spread in all directions by
people who say "my <foo> works better than your <bah>" (yours is one
of the few that turns this around and says "my <foo> works worse than
your <bah>").  I've been meaning to do some real tests some day, but
so far it's waiting on a tuit.

> However, NetBSD has been getting slower and should probably be
> audited for reasonable performance enhancements and delay abuses.

This sounds reasonable, if only to confirm whether it's true or not.

Finger for PGP public key
See complete headers for address and phone numbers