Will select() return before next jiffy if waiting on a high resolution timerfd?

Question

If I have

• A kernel with CONFIG_HIGH_RES_TIMERS=y,
• A coarse CONFIG_HZ (say, 100)
• and a file descriptor from timerfd_create with a sub-jiffy expiration

Should a call to select() on this timer return before the next jiffy, as say, clock_nanosleep would?

Answer 1

Both the select() timeout and the timerfd_create() timer are implemented with high-resolution timers on any recent kernel.