On Wed, Apr 21, 2010 at 11:26:07PM -0700, Darren Hart wrote: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?
IMHO, you don't need to do that.
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
This means lockdep has detect there is something wrong.
Can you show your 'dmesg'?
Thanks,
Yong
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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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