MacOS Performance – Task Manager for OS X El Capitan

How about this answer on another SE site?

https://superuser.com/questions/89266/whats-causing-all-the-disk-activity-on-os-x

From man iotop:

iotop tracks disk I/O by process, and prints a summary report that is refreshed every interval.

This is measuring disk events that have made it past system caches.

Since this uses DTrace, only the root user or users with the dtrace_kernel privilege can run this command.

This may not be precisely what you want - but it's a ksh script which wraps around dtrace, so you should be able to figure out how to make dtrace do what you need, if iotop doesn't handle it by default.

However, something like iotop -C 5 12 should give you something to start with: it will output 12 samples, each 5 seconds long.

Activity Monitor is the graphical application that comes with every OS X install for viewing and managing processes from your desktop.

You'll find it under Applications -> Utilities in a default OS X install.

In order to manage all the processes displayed in Activity Monitor you'll need an account with administrator privileges on the machine. With a lower privilege account you can only only manipulate your own processes or processes from groups to which you belong.

Here's a quick summary of the kinds of thinks you can accomplish with Activity Monitory. And a guide for finding out what's keeping your machine busy.

In particular, if you suspect you're running slow because of applications using excessive CPU, you'll want to click on the 'CPU' column header to sort applications by their CPU use. If you spot a few applications running hot you can use the search box to limit the Activity Monitor view to just a few applications.

The spinbox to the left of the search box contains some different view filters that can be handy. In particular I find the 'All Processes, Hierarchically' view to be valuable when it comes to tracing down parent processes of rogue child processes so you can see where things are coming from. It's a bit like pstree but interactive and continually updating.