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epoll_wait - waits for an I/O event on an epoll file descriptor


epoll_wait is a system call used to wait for I/O events on an epoll file descriptor. It is similar to poll, but with better scalability for large numbers of monitored file descriptors. It returns when either an I/O event has been detected or the timeout has expired.

The main advantage of using epoll_wait is increased scalability, since poll and select perform worse as the number of monitored events increases. However, there are some drawbacks to using epoll_wait. For example, epoll_wait is not a real-time system call, meaning that there can be a significant lag between events being triggered and them being handled by epoll_wait. Additionally, epoll_wait can be more complicated to use since it requires a more involved setup procedure.


  • epfd:int - the epoll file descriptor created with epoll_create
  • events:struct epoll_event*[U] - pointer to a buffer where the events will be returned
  • maxevents:int - the maximum number of events that can be returned
  • timeout:int - the timeout in milliseconds; or -1 to wait indefinitely

Available Tags

  • U - Originated from user space (for example, pointer to user space memory used to get it)






To trace I/O events on an epoll file descriptor

Example Use Case

An example use case for epoll_wait would be a real-time application that needs to process incoming network traffic.


There is a known bug in epoll_wait related to the maxevents argument. If the maxevents argument is greater than the number of available events, the timeout argument may not be taken into account correctly.

  • epoll_ctl - add or delete file descriptors to/from an epoll file descriptor
  • epoll_create - create a new epoll file descriptor
  • epoll_create1 - create a new epoll file descriptor

This document was automatically generated by OpenAI and needs review. It might not be accurate and might contain errors. The authors of Tracee recommend that the user reads the "events.go" source file to understand the events and their arguments better.