[petsc-users] our of core capability?

[Jed Brown]

On Wed, Nov 10, 2010 at 20:55, SUN Chun <Chun.SUN at 3ds.com> wrote:

> Sorry this might doesn't make any sense but I have to ask ... Does PETSc
> have the capability to use out-of-core disk space if I set a cap for memory
> usage? I looked around in the src but I could be missing something.
>

There is no explicit out-of-core capability, be warned that it will
unavoidably make things much slower (even if written specially for
out-of-core) but you could mmap a big file and have the matrices use that,
or you can just create a big swap file and let the OS handle it.  Note that
kernels can actually do a pretty good job of handling paging, so it's not a
clear win for an application to manage it themselves.  See e.g.
http://queue.acm.org/detail.cfm?id=1814327


> What I can think of is to use MatShell if that's the only option...
>

You can certainly do this, but if it makes sense to store your matrix in an
assembled format, you should probably just assemble it and let the OS handle
paging.

Jed
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