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    <head>
      <base href="https://bugs.llvm.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Tasking regression tests take 21mins"
   href="https://bugs.llvm.org/show_bug.cgi?id=51235">51235</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Tasking regression tests take 21mins
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>OpenMP
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Windows NT
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>enhancement
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>Runtime Library
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>llvm@meinersbur.de
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Execution time of the regression test have increased significantly from 1m20s
to ~21m. I am suspecting the following change to be responsible:
<a href="https://reviews.llvm.org/D106572">https://reviews.llvm.org/D106572</a>

Buildbot first occuring builds:
openmp-offload-cuda-runtime:
<a href="https://lab.llvm.org/staging/#/builders/154/builds/1717">https://lab.llvm.org/staging/#/builders/154/builds/1717</a>
openmp-offload-cuda-project:
<a href="https://lab.llvm.org/staging/#/builders/155/builds/2196">https://lab.llvm.org/staging/#/builders/155/builds/2196</a> (Build #2195 introduced
D106572)

Some tasking tests such as depend.cpp or gtid.cpp indeterministically take a
long time to complete without showing up as failed tests. In htop all threads
except one show up as busy-waiting with one in an interruptible sleep.

Attaching gdb to the test gtid showed the following stack traces:

Thread 7 (Thread 0x7fe945ae6700 (LWP 2647011)):
#0  futex_wait_cancelable (private=<optimized out>, expected=0,
futex_word=0x7fe948635868 <(anonymous
namespace)::hidden_helper_main_thread_cond_var+40>) at
../sysdeps/nptl/futex-internal.h:183
#1  __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x7fe948635800
<(anonymous namespace)::hidden_helper_main_thread_lock>, cond=0x7fe948635840
<(anonymous namespace)::hidden_helper_main_thread_cond_var>) at
pthread_cond_wait.c:508
#2  __pthread_cond_wait (cond=0x7fe948635840 <(anonymous
namespace)::hidden_helper_main_thread_cond_var>, mutex=0x7fe948635800
<(anonymous namespace)::hidden_helper_main_thread_lock>) at
pthread_cond_wait.c:638
#3  0x00007fe94860569b in __kmp_hidden_helper_main_thread_wait () from
/home/buildbot-worker/minipc-1050ti-linux/openmp-offload-cuda-project/llvm.build/lib/libomp.so
#4  0x00007fe9485a1ce4 in (anonymous
namespace)::__kmp_hidden_helper_wrapper_fn(int*, int*, ...) () from
/home/buildbot-worker/minipc-1050ti-linux/openmp-offload-cuda-project/llvm.build/lib/libomp.so
#5  0x00007fe94861eee3 in __kmp_invoke_microtask () from
/home/buildbot-worker/minipc-1050ti-linux/openmp-offload-cuda-project/llvm.build/lib/libomp.so
#6  0x00007fe9485a1aa1 in __kmp_invoke_task_func () from
/home/buildbot-worker/minipc-1050ti-linux/openmp-offload-cuda-project/llvm.build/lib/libomp.so
#7  0x00007fe9485abe6e in __kmp_fork_call () from
/home/buildbot-worker/minipc-1050ti-linux/openmp-offload-cuda-project/llvm.build/lib/libomp.so
#8  0x00007fe948596df7 in __kmpc_fork_call () from
/home/buildbot-worker/minipc-1050ti-linux/openmp-offload-cuda-project/llvm.build/lib/libomp.so
--Type <RET> for more, q to quit, c to continue without paging--
#9  0x00007fe9485aa764 in __kmp_hidden_helper_threads_initz_routine () from
/home/buildbot-worker/minipc-1050ti-linux/openmp-offload-cuda-project/llvm.build/lib/libomp.so
#10 0x00007fe948601afd in
__kmp_do_initialize_hidden_helper_threads::{lambda(void*)#1}::_FUN(void*) ()
from
/home/buildbot-worker/minipc-1050ti-linux/openmp-offload-cuda-project/llvm.build/lib/libomp.so
#11 0x00007fe948503609 in start_thread (arg=<optimized out>) at
pthread_create.c:477
#12 0x00007fe948428293 in clone () at
../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 8 (Thread 0x7fe9452e4800 (LWP 2647012)):
#0  0x00007fe94840b89b in sched_yield () at
../sysdeps/unix/syscall-template.S:78
#1  0x00007fe9485ce08a in bool __kmp_wait_template<kmp_flag_64<false, true>,
true, false, true>(kmp_info*, kmp_flag_64<false, true>*, void*) [clone
.constprop.0] () from
/home/buildbot-worker/minipc-1050ti-linux/openmp-offload-cuda-project/llvm.build/lib/libomp.so
#2  0x00007fe9485d7a7f in __kmp_fork_barrier(int, int) () from
/home/buildbot-worker/minipc-1050ti-linux/openmp-offload-cuda-project/llvm.build/lib/libomp.so
#3  0x00007fe9485a66b5 in __kmp_launch_thread () from
/home/buildbot-worker/minipc-1050ti-linux/openmp-offload-cuda-project/llvm.build/lib/libomp.so
#4  0x00007fe948601d57 in __kmp_launch_worker(void*) () from
/home/buildbot-worker/minipc-1050ti-linux/openmp-offload-cuda-project/llvm.build/lib/libomp.so
#5  0x00007fe948503609 in start_thread (arg=<optimized out>) at
pthread_create.c:477
#6  0x00007fe948428293 in clone () at
../sysdeps/unix/sysv/linux/x86_64/clone.S:95
[repeated for all other threads]</pre>
        </div>
      </p>


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