Examine the D scrypt: syscall::read:entry, syscall::write:entry
/pid == $1/ { ts[probefunc] = timestamp;
}
syscall::read:return, syscall::write:return
/pid == $1 && ts[probefunc] != 0/ { printf("%d nsecs", timestamp – ts[probefunc]); }
Which statement is true about this script?
A. It produces aggregations of system calls made by the process whose PID is passed as a command-line argument represented by $1. You see which system calls are issued, and how many times, over a fixed interval.
B. It produces elapsed times for reads and writes to the entry and returns DTrace probes for the process whose PID is passed as a command-line argument represented by $1.
C. It produces elapsed times between entry and return of read and write system calls for the process whose PID is passed as the first command-line argument to the D script, represented by $1.
D. It produces a measure of useful time spent in read and write system calls for the process whose PID is passed as a command-line argument represented by $1.
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