sendfile and tcp_nopush in Nginx - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the sendfile directive do in nginx?

The sendfile directive enables nginx to use the operating system's sendfile() system call to transfer files directly from disk to the network socket, improving performance by avoiding copying data between user space and kernel space.

beginner

What is the purpose of the tcp_nopush directive in nginx?

The tcp_nopush directive controls how nginx sends TCP packets. When enabled, it delays sending partial packets to send larger packets at once, reducing overhead and improving network efficiency.

intermediate

How do sendfile and tcp_nopush work together in nginx?

When sendfile is enabled, tcp_nopush helps by delaying packet sending until a full packet is ready. This combination improves file transfer speed and reduces CPU usage.

beginner

How do you enable sendfile and tcp_nopush in nginx configuration?

In the nginx configuration file, add these lines inside the http block:<br>

sendfile on;
tcp_nopush on;

beginner

What is a real-life analogy for sendfile and tcp_nopush working together?

Imagine sending a big package by mail. sendfile is like using a direct conveyor belt to move the package without extra handling. tcp_nopush is like waiting to fill the box completely before sealing it, so fewer boxes are sent and shipping is efficient.

What does enabling sendfile in nginx do?

A Caches files in memory

B Compresses files before sending

C Encrypts network traffic

D Transfers files directly from disk to network socket

Sendfile uses the OS system call to send files directly, improving performance.

What is the effect of enabling tcp_nopush in nginx?

A Forces immediate sending of all packets

B Delays sending partial TCP packets to send larger packets

C Disables TCP connections

D Splits packets into smaller pieces

Tcp_nopush delays sending to optimize packet size and reduce overhead.

Which nginx block typically contains sendfile on; and tcp_nopush on; directives?

A http

B server

C location

D events

These directives are usually set in the http block for global effect.

What is a benefit of using sendfile with tcp_nopush?

A Better logging of requests

B Increased file encryption

C Improved file transfer speed and reduced CPU usage

D Automatic file compression

They work together to optimize file sending and reduce CPU load.

If sendfile is off, what happens?

A Files are copied through user space before sending

B Files are sent directly from disk

C Network connections are closed

D Files are compressed automatically

Without sendfile, data moves through user space, which is slower.

Explain how sendfile and tcp_nopush improve nginx performance when serving static files.

Think about how data moves from disk to network and how packets are sent.

Describe how to enable sendfile and tcp_nopush in nginx and where to place these directives.

Consider nginx configuration structure and applying global settings.