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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif;color:#1F497D;mso-fareast-language:EN-US">I do not know what the default OpenMP stack size is on PPC, but the rest of your logic seems sound, and setting
</span><span style="font-size:10.0pt;font-family:"Lucida Console";color:#1F497D;mso-fareast-language:EN-US">OMP_STACKSIZE</span><span style="font-size:10.0pt;font-family:"Verdana",sans-serif;color:#1F497D;mso-fareast-language:EN-US"> seems entirely reasonable.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif;color:#1F497D;mso-fareast-language:EN-US">The standard says that the default stack size is “implementation defined”, so it is entirely reasonable that different implementations
have different default values.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif;color:#1F497D">-- Jim<br>
<br>
Jim Cownie <james.h.cownie@intel.com><br>
CVCG/DPD/TCAR (Technical Computing, Analyzers, and Runtimes)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif;color:#1F497D">Tel: +44 117 9071438</span><span style="color:#1F497D"><o:p></o:p></span></p>
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<p class="MsoNormal"><a name="_____replyseparator"></a><b><span lang="EN-US">From:</span></b><span lang="EN-US"> Openmp-dev [mailto:openmp-dev-bounces@lists.llvm.org]
<b>On Behalf Of </b>Simone Atzeni via Openmp-dev<br>
<b>Sent:</b> Monday, October 8, 2018 3:58 PM<br>
<b>To:</b> openmp-dev@lists.llvm.org<br>
<b>Subject:</b> [Openmp-dev] Default value for OpenMP thread stacksize<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US">HI all,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">What’s the default size for the stack of the OpenMP threads in x86 and and ppc64 in the OpenMP runtime?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I have a Fortran program which allocates more than a 1MB on the stack for each thread. On x86 runs correctly, but on ppc64 it seg faults.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I am seeing that each thread in x86 has a stacksize of 4096kb while on ppc64 is 1024kb.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">If I increase the stacksize with OMP_STACKSIZE the program runs correctly also on Power, but it fails if I only set “ulimit -s unlimited”, which make sense since ulimit should only change the stacksize for the main thread
but not for the other threads.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Is this the expected behavior and the correct solution is to set OMP_STACKSIZE?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Thanks.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Simone<o:p></o:p></span></p>
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