[petsc-users] mumps running out of memory, depending on an overall numerical factor?

Dominic Meiser dmeiser at txcorp.com
Wed Feb 5 15:09:21 CST 2014

On Wed 05 Feb 2014 01:36:29 PM MST, Barry Smith wrote:
> On Feb 5, 2014, at 2:05 PM, Jed Brown <jed at jedbrown.org> wrote:
>> Klaus Zimmermann <klaus.zimmermann at physik.uni-freiburg.de> writes:
>>> Isn’t that a bit pessimistic? After all there is the out-of-core
>>> facility with mumps.
>> I'll just note that out-of-core as an algorithmic device is dead on most
>> HPC machines.
>     But what about a non-HPC machine? Not everyone has huge machines but how about a well-endowed server quality workstation setup with the best disks available? Put as much physical memory as possible and then use the disks for out of core.

This approach has worked fairly well for me. I have a workstation with 
32GB of memory and 500GB on two SSD's in raid 0 configuration. The 
out-of-core files for the matrix I was trying to factor are about 300GB 
and the numerical factorization takes approximately 4hours. No idea how 
this compares to the performance one would get on a workstation that 
can fit the factors in ram. Perhaps not too big of a difference during 
the factorization but a faster solve?


>     Barry
>> There are a few machines with fast local SSD, but the
>> majority of HPC machines need about an hour to write the contents of
>> memory to disk.  You can get more memory by running on more cores up to
>> the entire machine.  If that's not enough, current computing awards
>> (e.g,, INCITE) are not large enough to store to disk at full-machine
>> scale more than a few times per year.

Dominic Meiser
Tech-X Corporation
5621 Arapahoe Avenue
Boulder, CO 80303
Telephone: 303-996-2036
Fax: 303-448-7756

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