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<div class="moz-cite-prefix">On 6/10/2012 11:42 PM, Jed Brown wrote:<br>
</div>
<blockquote
cite="mid:CAM9tzSnuU2nvc6d1Zy_=110Ew5hB7rpLfhCF_beubz4Ak8y4xg@mail.gmail.com"
type="cite">On Sat, Oct 6, 2012 at 4:19 PM, TAY wee-beng <span
dir="ltr"><<a moz-do-not-send="true"
href="mailto:zonexo@gmail.com" target="_blank">zonexo@gmail.com</a>></span>
wrote:<br>
<div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">May I know where can I
find all the options for GAMG? I can't find it in the
manual.<br>
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</blockquote>
<div><br>
</div>
<div>As always, run with -help. The options for GAMG
specifically are controlled under the prefix -pc_gamg_*. The
smoothers and coarse grid solvers are configured under
-mg_levels_*.</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000"> <br>
I also used -info for the GAMG and what does these mean:<br>
<br>
1. [9] MatAssemblyBegin_MPIAIJ(): Stash has 14396 entries,
uses 1 mallocs </div>
</blockquote>
<blockquote class="gmail_quote" style="margin:0 0 0
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<div bgcolor="#FFFFFF" text="#000000"> <br>
How serious is this? Does it mean there's a lot of mallocs
going on? Do I correct this by using higher d_nz and o_nz?<br>
</div>
</blockquote>
<div><br>
</div>
<div>No, the stash holds entries that are stored on a different
process from where you assemble. Assembling some values
off-process is common for finite element discretizations, for
example. Less than one percent of the values are assembled
off-process, which is fine.</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0
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<div bgcolor="#FFFFFF" text="#000000"> <br>
2. [4] MatAssemblyEnd_SeqAIJ(): Matrix size: 112785 X
112785; storage space: 0 unneeded,3628127 used<br>
[4] MatAssemblyEnd_SeqAIJ(): Number of mallocs during
MatSetValues() is 0<br>
[4] MatAssemblyEnd_SeqAIJ(): Maximum nonzeros in any row is
59<br>
<br>
When I use MatCreateAIJ, my d_nz and o_nz are both 7. If the
row is 59, does it mean that my d_nz and o_nz are too small.
Must I set it to the maximum nonzeros given by -info?<br>
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<div><br>
</div>
<div>Either this line is not the first assembly or you didn't
pass 7. If you don't want to use extra memory, you should
preallocate exactly, otherwise it is better to over-estimate
than to under-estimate.</div>
<div> </div>
</div>
</blockquote>
This line happens rather late in the assembly, so it is not the main
matrix which I've created, right? And hence this doesn't matter?<br>
<blockquote
cite="mid:CAM9tzSnuU2nvc6d1Zy_=110Ew5hB7rpLfhCF_beubz4Ak8y4xg@mail.gmail.com"
type="cite">
<div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0 0 0
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<div bgcolor="#FFFFFF" text="#000000"> <br>
3. [0] MatSetOption_SeqAIJ(): Option STRUCTURALLY_SYMMETRIC
ignored<br>
<br>
My Poisson matrix is symmetrical, so why is it ignored?</div>
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</div>
<br>
<div>This is a bad info message. That option is handled at a
higher level. I'll fix it.</div>
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