On 4/16/23 5:31?AM, wenyang.linux@xxxxxxxxxxx wrote: > From: Wen Yang <wenyang.linux@xxxxxxxxxxx> > > For the NON SEMAPHORE eventfd, if it's counter has a nonzero value, > then a read(2) returns 8 bytes containing that value, and the counter's > value is reset to zero. Therefore, in the NON SEMAPHORE scenario, > N event_writes vs ONE event_read is possible. > > However, the current implementation wakes up the read thread immediately > in eventfd_write so that the cpu utilization increases unnecessarily. > > By adding a configurable delay after eventfd_write, these unnecessary > wakeup operations are avoided, thereby reducing cpu utilization. What's the real world use case of this, and what would the expected delay be there? With using a delayed work item for this, there's certainly a pretty wide grey zone in terms of delay where this would perform considerably worse than not doing any delayed wakeups at all. -- Jens Axboe
