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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 - Threading.PhysicalConcurrency test fails when available cpus < physical cpus"
   href="https://bugs.llvm.org/show_bug.cgi?id=45556">45556</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Threading.PhysicalConcurrency test fails when available cpus < physical cpus
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>libraries
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>trunk
          </td>
        </tr>

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

        <tr>
          <th>OS</th>
          <td>Linux
          </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>Support Libraries
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>john.brawn@arm.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>If I do
 taskset -c 0 ./unittests/Support/SupportTests
--gtest_filter=Threading.PhysicalConcurrency
then the test fails with
 /home/jb/work/llvm-project/llvm/unittests/Support/Threading.cpp:25: Failure
 Expected: (Num.compute_thread_count()) <=
(hardware_concurrency().compute_thread_count()), actual: 4 vs 1

Num.compute_thread_count() examines /proc/cpuinfo which (on my machine) says
there are 4 cpus, hardware_concurrency().compute_thread_count() calls
sched_getaffinity which says there's one available cpu.

It looks like the commit that caused this to fail is:

commit 8404aeb56a73ab24f9b295111de3b37a37f0b841
Author: Alexandre Ganea <<a href="mailto:alexandre.ganea@ubisoft.com">alexandre.ganea@ubisoft.com</a>>
Date:   Thu Feb 13 22:49:57 2020 -0500

    [Support] On Windows, ensure hardware_concurrency() extends to all CPU
sockets and all NUMA groups</pre>
        </div>
      </p>


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