RELENG_4 -> 5 -> 6: significant performance regression

[Kris Kennaway]

On Fri, May 12, 2006 at 11:32:44PM +0300, Dmitry Pryanishnikov wrote:
> 
> Hello!
> 
> On Tue, 2 May 2006, Robert Watson wrote:
> >>options 	INVARIANTS
> >>options 	INVARIANT_SUPPORT
> >
> >In FreeBSD 5.x and FreeBSD 6.x, the INVARIANTS option has been 
> >significantly expanded to test a much larger set of invariants, and also 
> >incorporate kernel use-after-free checking, which involves memory 
> >scrubbing.  This is great for catching bugs, but it will have a 
> >significant performance impact, especially for kernel-intensive loads.
> 
>  So maybe it's time to add, say,
> 
> options      INVARIANTS_EXTENDED
> 
> for these new and expensive checks, and leave only basic and cheap (yet
> effective for bug hunting) asserts enabled when only
> 
> options      INVARIANTS
> 
> is defined?

No, they are all effective for bug hunting.  You just need to be aware
that it is incompatible with performance.

Kris
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