On 04/16/2019 12:50 PM, Davidlohr Bueso wrote: > On Sat, 13 Apr 2019, Waiman Long wrote: >> +/* >> + * We limit the maximum number of readers that can be woken up for a >> + * wake-up call to not penalizing the waking thread for spending too >> + * much time doing it. >> + */ >> +#define MAX_READERS_WAKEUP 0x100 > > Although with wake_q this is not really so... Could it at least be > rewritten, dunno something like so: > > /* > * Magic number to batch-wakeup waiting readers, even when writers > * are also present in the queue. This both limits the amount of > * work the waking thread must do (albeit wake_q) and also prevents > * any potential counter overflow, however unlikely. > */ >
The wording looks good to me. Will modify that for the next version. BTW, wake_q_add() has low overhead and so the lock hold time should be short. Outside the wait_lock, wake_up_q() still has a high overhead if there are many tasks to be woken up. Cheers, Longman
