<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: Times New Roman; font-size: 12pt; color: #000000'>As Jed points out, most of the time (~98%) is spent in your code rather than in the PETSc solver. Clearly, you need to profile your own source code and figure out<div>where the most time is spent. You can do this using the tools for user code profiling (PetscLogEvent and PetscLogStage) in PETSc. </div><div>Read Sections 11.2 and 11.3 of the User's Manual for more information on PetscLogEvent and PetscLogStage and also</div><div>look at examples such as </div><div>http://www.mcs.anl.gov/petsc/petsc-current/src/vec/vec/examples/tutorials/ex5.c.html</div><div>http://www.mcs.anl.gov/petsc/petsc-current/src/ksp/ksp/examples/tutorials/ex2.c.html</div><div>http://www.mcs.anl.gov/petsc/petsc-current/src/ksp/ksp/examples/tutorials/ex46.c.html</div><div><br></div><div>Shri<br><br><hr id="zwchr"><blockquote style="border-left:2px solid rgb(16, 16, 255);margin-left:5px;padding-left:5px;"><div class="gmail_quote">On Fri, Mar 16, 2012 at 14:52, <span dir="ltr"><<a href="mailto:Nan.Jia@dartmouth.edu" target="_blank">Nan.Jia@dartmouth.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Dear PETSc Group,<br>
I am tuning the efficiency of my PETSc code for a while, but get very little progress. So can anyone help me to analysis the log? Any suggestions will be appreciated.<br>
<br>
My problem is time dependent. At every time step, two about 6000 by 6000 sparse matrices need to be solved, which come from a Poisson equation. I use both sequential and parallel AIJ format to store matrices, but the performances are both not very good.<br>
</blockquote><div><br></div><div>1. You need to heed the huge warning</div><div><font face="'courier new', monospace"><br></font></div><div><div><font face="'courier new', monospace"> ##########################################################</font></div>
<div><font face="'courier new', monospace"> # #</font></div><div><font face="'courier new', monospace"> # WARNING!!! #</font></div>
<div><font face="'courier new', monospace"> # #</font></div><div><font face="'courier new', monospace"> # This code was compiled with a debugging option, #</font></div>
<div><font face="'courier new', monospace"> # To get timing results run config/configure.py #</font></div><div><font face="'courier new', monospace"> # using --with-debugging=no, the performance will #</font></div>
<div><font face="'courier new', monospace"> # be generally two or three times faster. #</font></div><div><font face="'courier new', monospace"> # #</font></div>
<div><font face="'courier new', monospace"> ##########################################################</font></div></div><div><br></div><div><br></div><div><br></div><div>2. You only spend 18 of 880 seconds in the solver. What do you want?</div>
<div><br></div>3. The problem is too small to get significant parallel speedup.</div><div class="gmail_quote"><br></div><div class="gmail_quote"><a href="http://www.mcs.anl.gov/petsc/documentation/faq.html#slowerparallel" target="_blank">http://www.mcs.anl.gov/petsc/documentation/faq.html#slowerparallel</a><br>
</div>
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