INVARIANTS (was Re: RELENG_4 -> 5 -> 6: significant performance regression)

[Matthew D. Fuller]

On Sat, May 13, 2006 at 11:58:26AM -0400 I heard the voice of
Kris Kennaway, and lo! it spake thus:
> 
> FYI, INVARIANTS adds checks but does not (is not supposed to) divert
> code paths.

It does at least in UMA; it does a lot of bzero()/NULL'ing out of
memory, which might hide later uninitialized-use bugs that could bite
you without it (and, of course, probably burns a fair chunk of CPU to
do it ;).  I know I've heard other cases over the past 5 years or so;
that's the only one I've heard recently or can check, but I wouldn't
be too surprised if there were others.


-- 
Matthew Fuller     (MF4839)   |  fullermd at over-yonder.net
Systems/Network Administrator |  http://www.over-yonder.net/~fullermd/
           On the Internet, nobody can hear you scream.