Hi,
I am having a bit of a problem understanding the following output from
plockstat:
# plockstat -H -p `pgrep mcon`
Mutex hold
Count nsec Lock Caller
-------------------------------------------------------------------------------
1955045 2195 libc.so.1`libc_malloc_lock mcon`addwork+0x92
1949696 2196 libc.so.1`libc_malloc_lock mcon`dowork+0x18b
From taking a quick look at plockstat.c, the nsec column is a sum
of the number of nanoseconds that a mutex is held. Count is a count
of the number of times the mutex is acquired.
According to this output, a malloc lock is aquired and released
approximately 4 million times, but the total time spent holding the lock
is approximately 4000 nsecs. So, on average, the lock is held for
4000nsec/4000000
or .001 nsecs!!! I did not think my machine was so fast! If I use the
plockstat
provider directly with dtrace, I get reasonable results.
So, is my arithmetic wrong, or is there another explanation?
thanks,
max
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