EPOLLEXCLUSIVE Limits Wakeups Across epoll Instances

Wed, 23 Sep 2026 00:00:00 +0000

EPOLLEXCLUSIVE Limits Wakeups Across epoll Instances

EPOLLEXCLUSIVE changes event distribution when several epoll instances register the same target file description. Without the flag, a readiness event can wake waiters associated with every interested epoll instance. With exclusive registrations, Linux can restrict that fan-out and reduce redundant wakeups.

The flag does not make delivery single-consumer, does not assign ownership of the target, and does not replace application-level coordination. Its contract is narrower: among epoll instances that registered a target with EPOLLEXCLUSIVE, one or more receive an event for a wakeup rather than requiring all of them to receive it.

signalfd Consumes Blocked Signals Through File Descriptor Reads

Wed, 23 Sep 2026 00:00:00 +0000

signalfd Consumes Blocked Signals Through File Descriptor Reads

signalfd() turns selected signal notifications into records that can be consumed with read(). A matching pending signal makes the descriptor readable, which allows signal handling to share the same poll(), select(), or epoll path as sockets, timers, and other descriptors.

The descriptor does not redirect signals merely because its mask names them. Normal signal-mask rules still apply. In the usual design, the selected signals are blocked before they can be delivered through their ordinary dispositions, then a signalfd reads the pending instances.

Event Notification on Nalar

EPOLLEXCLUSIVE Limits Wakeups Across epoll Instances

EPOLLEXCLUSIVE Limits Wakeups Across epoll Instances

signalfd Consumes Blocked Signals Through File Descriptor Reads

signalfd Consumes Blocked Signals Through File Descriptor Reads