I'm having some trouble with lockstat. I've enabled CONFIG_LOCK_STATS
and then run the following commands to collect the lock statistics for
the futex_lock test case. I expect this test case to generate a fair
amount of contention on the futex hash bucket locks, but they don't show
up in the stats (in fact, nothing shows up in the stats). I have seen
much longer lock_stat files when I forgot to clear them before the test,
but no hb locks showed up there either.
Is my usage below incorrect? Do I have to somehow annotate the hb->lock
in order for lockstat to track it?
This is as of:
commit a3d3203e4bb40f253b1541e310dc0f9305be7c84
Merge: f937331... ec28dcc...
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sun Mar 14 20:29:21 2010 -0700
# echo 0 > /proc/lock_stat; echo 1 > /proc/sys/kernel/lock_stat;
./futex_lock -i10000000 -p1000 -d20; cat /proc/lock_stat >
lock.lockstat; echo 0 > /proc/sys/kernel/lock_stat
futex_lock: Measure FUTEX_LOCK operations per second
Arguments: iterations=10000000 threads=256 adaptive=no
period=1000 duty-cycle=20%
Result: 731 Kiter/s
# cat lock.lockstat
lock_stat version 0.3
*WARNING* lock debugging disabled!! - possibly due to a lockdep warning
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
class name con-bounces contentions
waittime-min waittime-max waittime-total acq-bounces
acquisitions holdtime-min holdtime-max holdtime-total
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
#
Thanks,
--
Darren Hart
IBM Linux Technology Center
Real-Time Linux Team
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