[petsc-users] memory use of a DMDA

Juha Jäykkä juhaj at iki.fi
Mon Oct 28 05:27:07 CDT 2013

> > For comparison, 3.4.2 gives (from the previous email): 354 MiB for 1
> > rank, 141 for 2 ranks and 81 for 4 ranks, which is a LOT less. I
> > suspect this might have something to do with the DA -> DMDA change?
> Hmm, I wonder where you're getting your numbers from.

>From /proc/self/stat, which (for me at least) gives exactly the same number as 
psutil.Process(os.getpid()).get_memory_info().rss (I suspect psutil actually 
reads /proc/self/stat as well).

Which brings up a point of your numbers

>   $ mpirun.hydra -np 1 python2 -c "$CMD"
>   8 MiB /
>   29 MiB
>   226 MiB

etc are way lower than mine. They are more or less in-line with my 3.2 tests, 
so something does not add up. My guess is "--with-64-bit-indices": if yours is 
with 32-bit indices, it's obvious you will get less memory consumption. Now, I 
need to apologise: my 3.2 test had 32-bit indices and all the old numbers I 
had for 3.3 did, tooo, but my 3.4.2 has 64-bit. I lately had to switch to 64-
bit indices and that just happened to coincide with the move to 3.4 series.

Perhaps this explains everything? (Of course, Barry's patch is still a good 

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