Examine the D scrypt: syscall::read:entry, syscall::write:entry /pid ==$1/
{
ts[probefunc] = timestamp;
}
syscall::read:retum, syscall::write:retum /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.
D
D