/usr/bin/time is a useful command (not to confuse with “time”) that can measure “real,user,sys”, but also “maximum resident set size, page faults, swaps” and other very useful system info for a specific program.
In GNU stack based unix, just do /usr/bin/time
In BSD based stack (mac), you need /usr/bin/time -lp
“time” command is a shell script in bash, not the same as the builtin linux function
http://stackoverflow.com/questions/19236448/shell-execution-time-vs-usr-bin-time
http://man7.org/linux/man-pages/man1/time.1.html
I believe the /usr/bin/time actually calls the system function “getrusage” http://linux.die.net/man/2/getrusage
which can give the resources statistics as shown in /usr/bin/time
A sample output is shown here
real 0.00
user 0.00
sys 0.00
688128 maximum resident set size
0 average shared memory size
0 average unshared data size
0 average unshared stack size
180 page reclaims
0 page faults
0 swaps
0 block input operations
0 block output operations
0 messages sent
0 messages received
0 signals received
0 voluntary context switches
1 involuntary context switches
Another example output
99.21user 49.40system 2:06.92elapsed 117%CPU (0avgtext+0avgdata 3556152maxresident)k
This shows that it spent 99s in user program, 50s in system kernels, total elapsed time is 2 min and 6 s. There is an average of 117% CPU utilization. This shows it is mostly single threaded.
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