> On Wed, Jun 5, 2019 at 9:25 PM 김규래 <msc...@naver.com> wrote: > > > Hi, thanks for the detailed explanation. > > I think I now get the picture. > > Judging from my current understanding, the task-parallelism currently works > > as follows: > > 1. Tasks are placed in a global shared queue. > > 2. Workers consume the tasks by bashing the queue in a while loop, just as > > self-scheduling (dynamic scheduling)/ > > > > Then the improvements including work-stealing must be done by: > > 1. Each worker holds a dedicated task queue reducing the resource > > contention. > > 2. The tasks are distributed in a round-robin fashion
> For nested task submission (does OpenMP support that?) you probably > want to submit to the local queue rather than round-robin, no? Hi Janne, I believe you're talking about spawning child tasks within an already running task, which I believe is supported by OpenMP. In this case, pushing to the local queue could introduce a deadlock if the master thread waits on the spawned tasks. A short one though since work-stealing can resolve the deadlock. A better way to handle this is to round-robin the child tasks to the queues excluding the queue of the thread consuming the current task. Then waiting on the tasks should never cause a deadlock. Or did I misunderstand your question? Maybe there is a specific reason for avoiding avoid round-robin that I missed? Ray Kim
