Level Triggered

Definitions

1. An I/O notification mode in which the operating system repeatedly reports that a file descriptor is ready as long as the condition persists (e.g., data remains in the read buffer), as opposed to edge-triggered mode which only notifies once when the state changes. Level-triggered is the default behavior for select, poll, and epoll.

   In plain English: A way for the operating system to keep reminding a program that data is available until the program actually reads it, rather than telling it only once.

   Example: "We switched from level-triggered to edge-triggered epoll because the level-triggered notifications were firing thousands of times per second on a busy socket we hadn't drained yet."

Related Terms

• Memory Alignment
• Memory Layout
• Memory Zeroing
• Microkernel
• Multiplexing
• Qemu
• Raw Pointer
• Signal Handler