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Document WITNESS_PROFILING.

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Submitted by:	Hiten Pandya <hiten@uk.FreeBSD.org>
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Dag-Erling Smørgrav 2002-04-15 19:42:15 +00:00
parent b32ecb502b
commit 4db0d7f16f
1 changed files with 22 additions and 0 deletions
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sys/conf/NOTES
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@ -134,6 +134,28 @@ options WITNESS
options WITNESS_DDB
options WITNESS_SKIPSPIN
#
# MUTEX_PROFILING - Profiling mutual exclusion locks (mutexes). This
# records four numbers for each acquisition point (identified by
# source file name and line number): longest time held, total time held,
# number of non-recursive acquisitions, and average time held. Measurements
# are made and stored in nanoseconds (using nanotime(9)), but are presented
# in microseconds, which should be sufficient for the locks which actually
# want this (those that are held long and / or often). The MUTEX_PROFILING
# option has the following sysctl namespace for controlling and viewing its
# operation:
#
# debug.mutex.prof.enable - enable / disable profiling
# debug.mutex.prof.acquisitions - number of mutex acquisitions held
# debug.mutex.prof.records - number of acquisition points recorded
# debug.mutex.prof.maxrecords - max number of acquisition points
# debug.mutex.prof.rejected - number of rejections (due to full table)
# debug.mutex.prof.hashsize - hash size
# debug.mutex.prof.collisions - number of hash collisions
# debug.mutex.prof.stats - profiling statistics
#
options MUTEX_PROFILING
#####################################################################
# COMPATIBILITY OPTIONS