The CUSP case wouldn't help because chances are you are not holding
memory in CUSP format living on the device.
That makes sense.
Thanks for the help, Jed.
On Thu, Aug 23, 2012 at 11:40 AM, Jed Brown jedbrown at mcs.anl.gov wrote:
On Thu, Aug 23, 2012 at 1:25 PM, Mohammad Mirzadeh mirzadeh at
gmail.comwrote:
Hi guys,
I've added a small function to only solve the linear system in parallel
for problems that are not big enough to justify parallelizing the whole
thing but would still take some time to solve in serial -- so far It's been
handy. To prevent extra copy from my own format to petsc's, I'm using
VecCreateMPIWithArray and MatCreateMPIWithSplitArray functions and they
work with MPI on very few processes (like 4 or so). I have a couple of
questions:
1) Is it worth considering using pThread and/or CUSP versions of the
matrices for such problems?
The old pthread types are being removed in favor of threading support for
normal formats.
2) If so, what would be a better approach. Using hardwired vector types
in the code or using generic VecCreate functions to be able to change the
type at run-time?
Just use VecSetType()/MatSetType() to switch. You should really profile
just using MatSetValues() to assemble. It's very likely that you are
needlessly complicating your code by trying to skip a copy.
3) Are there equivalent versions of XXXWithArray functions for CUSP and
pThread types? I don't seem to find them in manual page.
The CUSP case wouldn't help because chances are you are not holding memory
in CUSP format living on the device.
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