<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<p>Hi,</p>
<p>I have been PETSc together with my CFD code. There seems to be a
bug with the Intel compiler such that when I call some DM routines
such as DMLocalToLocalBegin, a segmentation violation will occur
if full optimization is used. I had posted this question a while
back. So the current solution is to use -O1 -ip instead of -O3
-ipo -ip for certain source files which uses DMLocalToLocalBegin
etc.<br>
</p>
<p>Recently, I made some changes to the code, mainly adding some
stuffs. However, depending on my options. some cases still go thru
the same program path.</p>
<p>Now when I tried to run those same cases, I got segmentation
violation, which didn't happen before:</p>
<p><i> IIB_I_cell_no_uvw_total2 14 10
6 3</i><i><br>
</i><i>
2 1</i></p>
<p><i>[0]PETSC ERROR:
------------------------------------------------------------------------</i><i><br>
</i><i>[0]PETSC ERROR: Caught signal number 11 SEGV: Segmentation
Violation, probably memory access out of range</i><i><br>
</i><i>[0]PETSC ERROR: Try option -start_in_debugger or
-on_error_attach_debugger</i><i><br>
</i><i>[0]PETSC ERROR: or see
<a class="moz-txt-link-freetext" href="http://www.mcs.anl.gov/petsc/documentation/faq.html#valgrind">http://www.mcs.anl.gov/petsc/documentation/faq.html#valgrind</a></i><i><br>
</i><i>[0]PETSC ERROR: or try <a class="moz-txt-link-freetext" href="http://valgrind.org">http://valgrind.org</a> on GNU/linux and
Apple Mac OS X to find memory corruption errors</i><i><br>
</i><i>[0]PETSC ERROR: configure using --with-debugging=yes,
recompile, link, and run </i><i><br>
</i><i>[0]PETSC ERROR: to get more information on the crash.</i><i><br>
</i><i>[0]PETSC ERROR: --------------------- Error Message
--------------------------------------------------------------</i><i><br>
</i><i>[0]PETSC ERROR: Signal received</i><i><br>
</i><i>[0]PETSC ERROR: See
<a class="moz-txt-link-freetext" href="http://www.mcs.anl.gov/petsc/documentation/faq.html">http://www.mcs.anl.gov/petsc/documentation/faq.html</a> for trouble
shooting.</i><i><br>
</i><i>[0]PETSC ERROR: Petsc Release Version 3.7.4, Oct, 02, 2016
</i><i><br>
</i><i>[0]PETSC ERROR: ./a.out </i>
<br>
</p>
<p>I can't debug using VS since the codes have been optimized. I
tried to print messages (if (myid == 0) print "1") to pinpoint the
error. Strangely, after adding these print messages, the error
disappears.</p>
<p><i> IIB_I_cell_no_uvw_total2 14 10
6 3</i><i><br>
</i><i> 2 1</i><i><br>
</i><i> 1</i><i><br>
</i><i> 2</i><i><br>
</i><i> 3</i><i><br>
</i><i> 4</i><i><br>
</i><i> 5</i><i><br>
</i><i> 1 0.26873613 0.12620288 0.12949340
1.11422363 0.43983516E-06 -0.59311066E-01 0.25546227E+04</i><i><br>
</i><i> 2 0.22236892 0.14528589 0.16939270
1.10459102 0.74556128E-02 -0.55168234E-01 0.25532419E+04</i><i><br>
</i><i> 3 0.20764796 0.14832689 0.18780489
1.08039569 0.80299767E-02 -0.46972411E-01 0.25523174E+04</i></p>
<p>Can anyone give a logical explanation why this is happening?
Moreover, if I removed printing 1 to 3, and only print 4 and 5,
segmentation violation appears again.</p>
<p>I am using Intel Fortran 2016.1.150. I wonder if it helps if I
post in the Intel Fortran forum.</p>
<p>I can provide more info if require.<br>
</p>
<p><br>
</p>
<pre class="moz-signature" cols="72">--
Thank you very much.
Yours sincerely,
================================================
TAY Wee-Beng (Zheng Weiming) 郑伟明
Personal research webpage: <a class="moz-txt-link-freetext" href="http://tayweebeng.wixsite.com/website">http://tayweebeng.wixsite.com/website</a>
Youtube research showcase: <a class="moz-txt-link-freetext" href="https://www.youtube.com/channel/UC72ZHtvQNMpNs2uRTSToiLA">https://www.youtube.com/channel/UC72ZHtvQNMpNs2uRTSToiLA</a>
linkedin: <a class="moz-txt-link-abbreviated" href="http://www.linkedin.com/in/tay-weebeng">www.linkedin.com/in/tay-weebeng</a>
================================================</pre>
</body>
</html>