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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Reduction across teams hangs at __kmpc_end_reduce()"
href="https://llvm.org/bugs/show_bug.cgi?id=30890">30890</a>
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<th>Summary</th>
<td>Reduction across teams hangs at __kmpc_end_reduce()
</td>
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<th>Product</th>
<td>OpenMP
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>All
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Runtime Library
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>grokos@us.ibm.com
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<th>Classification</th>
<td>Unclassified
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<p>
<div>
<pre>Tested on x86_64 and ppc64le, RHEL.
The following code which involves a reduction across teams when target
offloading is disabled never runs to completion.
#include <omp.h>
int main() {
int nthreads = 0;
#pragma omp target teams num_teams(4) map(tofrom: nthreads) \
if(target:0) reduction(+:nthreads)
{
nthreads = omp_get_num_threads();
}
return 0;
}
Execution freezes while calling __kmpc_end_reduce(). It seems threads are
spinning forever at a hyper-barrier (__kmp_hyper_barrier_gather()).</pre>
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