panic in recent RELENG_5 tcp code path

Gleb Smirnoff glebius at
Fri May 20 06:15:46 PDT 2005


On Fri, May 20, 2005 at 03:10:32PM +0200, Jeremie Le Hen wrote:
J> > according to the fact that the panic occured in dereferncing mbuf pointer
J> > your kernel is compiled without INVARIANTS.
J> > 
J> > Please compile it with INVARIANTS. This will probably help to trigger panic
J> > earlier, and it will be more clear.
J> a quick look at src/conf/NOTES reveals the following :
J> %%%
J>     #
J>     # The INVARIANTS option is used in a number of source files to enable
J>     # extra sanity checking of internal structures.  This support is not
J>     # enabled by default because of the extra time it would take to check
J>     # for these conditions, which can only occur as a result of
J>     # programming errors.
J>     #
J> %%%
J> I'm going to recompile my kernel with INVARIANTS but I wonder in
J> which order of magniture it will slow my kernel down.  In other words,
J> what does INVARIANTS do concretely, shall I expect a performance drop
J> like WITNESS does ?

No. The performance loss is _much_ less significant than in WITNESS case.
You probably will not notice it.

Totus tuus, Glebius.

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