[Openmp-commits] [PATCH] D77609: [OpenMP][WIP] Added the support for unshackled task in RTL

Alex via Phabricator via Openmp-commits openmp-commits at lists.llvm.org
Tue Sep 1 04:57:23 PDT 2020

adurang added inline comments.

Comment at: openmp/runtime/src/kmp_tasking.cpp:3771
+  if (task_team)
+    while (KMP_ATOMIC_LD_ACQ(&task_team->tt.tt_unfinished_unshackled_tasks))
+      ;
tianshilei1992 wrote:
> tianshilei1992 wrote:
> > adurang wrote:
> > > It seems to me that this is forcing any taskwait (and possibly taskgroup) to wait for any outstanding "async target" that exist on the team irrespectively of being a part of that synchronization domain or not. 
> > Not any async target. Only those created in the team.
> Sorry I still didn't understand this part. Could you please expatiate it?

For the code below:

#pragma omp parallel num_threads(2)
#pragma omp target nowait
#pragma omp taskwait

With your current code (because you're using a shared counter for the whole team), both thread 1 and 2 are waiting for each others target regions ( so for example, even if target-th1 was finished thread1 would be blocked until target-th2 was completed). Each taskwait should only be waiting for their own child target tasks. 

Hope this helps.

  rG LLVM Github Monorepo



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