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Client-Server Number of Copies

Question Text​

The server in the image below uses regular TCP sockets to handle the connection and send() to send the data. How many times are the contents of the file copied by the server while being sent to the client?

Client-Server Steps

Question Answers​

  • 2

  • 1

  • 4
  • 3

Feedback​

Remember double buffering! When the app calls read(), the server's kernel will first save the file to an internal buffer destined for reading. Then the app will copy the file to its own buffer. Following this step, the app will call send(), which will first copy the file to a buffer in the kernel. From this buffer, the kernel itself will copy the file to another buffer on the NIC (Network Interface Card). In total, there the file is copied 4 times, as outlined in the image below.

Server Copies - Read-Send