Apple Open Source: the drivers

David A. Gatwood marsmail at
Thu Mar 18 11:46:56 EST 1999

On Wed, 17 Mar 1999, Hollis R Blanchard wrote:

> And another question: how is it that OS X, based on Mach, is still comparable
> in speed to other non-microkernel operating systems? It was my (uneducated)
> impression that one of the tradeoffs of a microkernel was a performance
> penalty.

There is a performance penalty, but not very much.  This is substantially
reduced when the server is collocated (loaded into kernel space), since
this eliminates the need for message passing.  The reason MkLinux has a
bigger speed tradeoff has less to do with the MK architecture and more to
do with slow legacy drivers. Many of MkLinux's drivers can be traced back
for a number of years (some, like the serial driver, may even date back to
pre-Mac days -- not positive, though).  Since MacOS X and X Server use
different drivers (with different driver frameworks, etc.), they should
perform better because of that alone.  Apple's compiler optimization no
doubt helps, too, though. :-)


David A. Gatwood                         Visit globegate's internet
dgatwood at                  talker, Deep Space 36                telnet

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