On Wed, Jun 14, 2006 at 10:21:44AM -0400, John Baldwin wrote: > On Wednesday 14 June 2006 05:54, John Birrell wrote: > > > > critical_enter 4364385478 > > > > critical_exit 4364385478 > > > > The points I wanted to make about these calls are: > > > > 1. critical_enter is called so often that the debug printf that /could/ > > be compiled into it should cause an increase in global warming if > > you tried. 8-) > > No, it's not a printf to the console it's a printf into the a circular > buffer (see options KTR) and the system has been run with it enabled w/o > burning the machine up. :) For point of comparison, I added an implementation of spinlock profiling in my kris-contention p4 branch which does a KTR every 100 mtx_lock_spin() operations, and this has less than 5% performance impact. KTR is very cheap since it is just a single atomic op to increment the buffer index, and then a couple of pointer assignments. Kris
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