<html>#1326: running loopcontrol on strange number of threads fails
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<tr><td style='text-align:right'> Reporter:</td><td>Roland Haas</td></tr>
<tr><td style='text-align:right'> Status:</td><td>new</td></tr>
<tr><td style='text-align:right'>Milestone:</td><td></td></tr>
<tr><td style='text-align:right'> Version:</td><td></td></tr>
<tr><td style='text-align:right'> Type:</td><td>bug</td></tr>
<tr><td style='text-align:right'> Priority:</td><td>minor</td></tr>
<tr><td style='text-align:right'>Component:</td><td>EinsteinToolkit thorn</td></tr>
</table>
<p>Comment (by Steven R. Brandt):</p>
<p>I recently attempted to run the gallery example on Deep Bayou. I set OMP_NUM_THREADS=4, and asked for 12 procs to run on the node (which has 48 cores according to lscpu). Cactus failed with this message cactus_sim: /nvme/sbrandt/Cactus/arrangements/Carpet/LoopControl/src/loopcontrol.cc:264: T <unnamed>::divexact(T, T) [with T = int]: Assertion <code>i % j == 0' faile</code></p>
<p>It also said <code>INFO (Carpet): This process runs on 24 cores</code>. At Roland’s suggestion, I tried adding <code>LoopControl::use_smt_threads = "no"</code> to the par file and all was well. Maybe “no” is a more sensible default? </p>
<div class="codehilite"><pre><span></span><span class="n">Architecture</span><span class="o">:</span> <span class="n">x86_64</span>
<span class="n">CPU</span> <span class="n">op</span><span class="o">-</span><span class="n">mode</span><span class="o">(</span><span class="n">s</span><span class="o">):</span> <span class="mi">32</span><span class="o">-</span><span class="n">bit</span><span class="o">,</span> <span class="mi">64</span><span class="o">-</span><span class="n">bit</span>
<span class="n">Byte</span> <span class="n">Order</span><span class="o">:</span> <span class="n">Little</span> <span class="n">Endian</span>
<span class="n">CPU</span><span class="o">(</span><span class="n">s</span><span class="o">):</span> <span class="mi">48</span>
<span class="n">On</span><span class="o">-</span><span class="n">line</span> <span class="n">CPU</span><span class="o">(</span><span class="n">s</span><span class="o">)</span> <span class="n">list</span><span class="o">:</span> <span class="mi">0</span><span class="o">-</span><span class="mi">47</span>
<span class="n">Thread</span><span class="o">(</span><span class="n">s</span><span class="o">)</span> <span class="n">per</span> <span class="n">core</span><span class="o">:</span> <span class="mi">1</span>
<span class="n">Core</span><span class="o">(</span><span class="n">s</span><span class="o">)</span> <s
<p>--<br/>
Ticket URL: <a href='https://bitbucket.org/einsteintoolkit/tickets/issues/1326/running-loopcontrol-on-strange-number-of'>https://bitbucket.org/einsteintoolkit/tickets/issues/1326/running-loopcontrol-on-strange-number-of</a></p>
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