On 22-Feb-01 Dag-Erling Smorgrav wrote:
> John Baldwin <[EMAIL PROTECTED]> writes:
>> On 22-Feb-01 Maxim Sobolev wrote:
>> Hmm, ouch, you do'nt want MUTEX_DEBUG, that'll slow your system to a crawl.
> For the same reason, you probably want WITNESS_SKIPSPIN.

Not really.  WITNESS doesn't really bog down spin mutexes all that much.  It
has a very simple order checking that is nothing like the order checking for
sleep mutexes.  The killer for MUTEX_DEBUG is that each mtx_init() involves
walking a linked list of _all_ of the mutexes in the system and checking each
one with the one beign init'd to check for a duplicate init.

> WITNESS_DDB is a bad idea, BTW, there's a (presumably harmless) lock
> order reversal in the FS code that you're practically guaranteed to to
> hit during boot.

Well, they aren't necessarily harmless, but they've been around for a very long
time, so if they do cause rare lockups, they are rare at least.

> -- 
> Dag-Erling Smorgrav - [EMAIL PROTECTED]


John Baldwin <[EMAIL PROTECTED]> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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