Say you want to know how often you're allocating tiles in Firefox or the rate of some other thing. There's an easy way to do this using dtrace. The following dtrace script counts calls to any functions matching the pattern '*SharedMemoryBasic*Create*' in XUL in the target process.

#pragma D option quiet
dtrace:::BEGIN
{
    rate = 0;
}

profile:::tick-1sec
{
    printf("%d/sec\n", rate);
    rate = 0;
}

pid$target:XUL:*SharedMemoryBasic*Create*:entry
{
    rate++;
} 

You can run this script with following command:

$ dtrace -s $SCRIPT_NAME -p $PID

I'd be interested in knowing if anyone else has a similar technique for OSs that don't have dtrace.

http://muizelaar.blogspot.com/2016/07/counting-function-calls-per-second.html