kc3-lang/libevent

2012-04-26T16:22:03

When PRECISE_TIMERS is set with epoll, use timerfd for microsecond precision The epoll interface ordinarily gives us one-millisecond precision, so on Linux it makes perfect sense to use the CLOCK_MONOTONIC_COARSE timer. But when the user has set the new PRECISE_TIMER flag for an event_base (either by the EVENT_BASE_FLAG_PRECISE_TIMER flag, or by the EVENT_PRECISE_TIMER environment variable), they presumably want finer granularity. On not-too-old Linuxes, we can achieve this using the Timerfd mechanism, which accepts nanosecond granularity and understands posix clocks. It's a little more expensive than just calling epoll_wait(), so we won't do it by default.