Subject: Re: Real vfork() (was: third results)
To: None <tooleym@douglas.bc.ca>
From: Jason Thorpe <thorpej@nas.nasa.gov>
List: tech-kern
Date: 04/15/1998 22:25:35
On Wed, 15 Apr 1998 22:10:18 -0700 (PDT)
tooleym@douglas.bc.ca wrote:
> For god's sake! Someone post some concrete, verifiable, non-arguable
> message and end it! I beg you!
If you insist! :-)
Here are the facts:
* NetBSD's new vfork(2) implements the pre-4.4BSD semantics.
* The vmspace-sharing piece is faster than even the best COW
algorithm.
* The original pre-4.4BSD vfork(2) semantics are now specified
in XPG4.2. This means that new systems that want to carry the
UNIX(tm) trademark must implement the address space-sharing
semantics. I.e. the interface is compatible with the rest of
the industry.
* There is a noticeable performance improvement, especially
for large processes, e.g. make(1) bulding the C library or
kernel.
* The change was discussed at length with members of Core and
the developer of NetBSD's new VM system (UVM), Chuck Cranor.
Given these, plus the fact that I wrote NetBSD's new vfork(2) implementation,
it's not likely that I'm going to be swayed back to a 4.4BSD vfork(2).
Jason R. Thorpe thorpej@nas.nasa.gov
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