I asked BDE about the same thing off-list:
Yes, the debug options (INVARIANTS and WITNESS,
especially the latter)
slow down the kernel by a factor of 10 or so. Only
progams that don't
make many syscalls run reasonably fast. I only turn
on these options
for debugging (not often). Without them, syscalls
should be an average
of only (sigh) about 10% slower in -current.
--- "M. Warner Losh" <[EMAIL PROTECTED]> wrote:
> In message: <email@example.com>
> Garance A Drosihn <[EMAIL PROTECTED]>
> : Could it be due to the DDB, INVARIANTS & WITNESS
> options in the
> : kernel? If it is that's fine with me, I'm just
> wondering where
> : that magnitude of a slowdown would be coming from.
> No way for DDB, Maybe for Invariants, almost
> certainly for witness.
> WITNESS is slow and tends to exagerate lock
> contention stalls (or so
> it seems).
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