Long description

Part (a): On the left, the sender running a process is shown as a wavy line, there is a downward arrow labeled Trap to the kernel, sender blocked from a running process. On the right, an upward arrow labeled return from the kernel, sender released. This upward arrow points to another process sent by the sender and is shown as a wavy line. In between, from left to right between processes, on the top, a bidirectional arrow labeled Sender blocked. Similarly, at the bottom, a bidirectional arrow labeled the message being sent. Part (b): On the left, the sender running a process is shown as a wavy line, there is a downward arrow labeled Trap, sender blocked from a running process. On the right, an upward arrow labeled return, sender released is shown as a wavy line. This upward arrow points to another process sent by the sender. In between, from left to right between processes, on the top, a bidirectional arrow labeled Sender blocked. Similarly, at the bottom, a bidirectional arrow labeled the message copied to a kernel buffer. Also, when the second process is running, at the bottom, a bidirectional arrow labeled the message being sent.