PetscMemoryGetMaximumUsage

[Sh.M]

Hi again,

I am using the function and when solving a system with 32 CPUs I get that

CPU 0 - max memory usage 10GB(this is mostly due to it reading the matrix
from file(5GB file),  constructing it and then assembling/distributing it)

CPU 1-31 = max memory usage 675MB per CPU. The maximum amount of memory used
per CPU is during solve.

Total memory usage: 31GB

The OS does not release the 10GB memory CPU 0 is occupying wich is a bit
annoying and I can attest to that as when I do operations with CPU 0 as in
reading another matrix, the memory usage that the OS is reporting is not
increasing, it stays at 10GB even though I just read another matrix into the
memory. So while the memory is definitely "freed", it is not released by CPU
0 and This seems to be an OS configuration thing I guess.

So my problem is that I have no idea how much memory CPU 0 is actually using
during the solve.

Can you give a hint or advice on how I should calculate CPU 0 memory usage
during solve? Would it be roughly 675MB as the other CPUs aswell?

Would the total memory usage during solve actually be closer to
22GB(32*675MB) rather than the 31GB(20GB+31*675MB) that I naively
calculated?

With best regards, Shaman Mahmoudi

----- Original Message ----- 
From: "Barry Smith" <bsmith at mcs.anl.gov>
To: <petsc-users at mcs.anl.gov>
Sent: Monday, May 08, 2006 9:31 PM
Subject: Re: PetscMemoryGetMaximumUsage


>
>    Unfortunately that routine is not currently "wired"; getting actual
> memory usage is not portable and is a pain.
>
>    You can use PetscMallocGetMaximumUsage() to see the maximum amount
> of memory PETSc has allocated at any one time (in all the PETSc objects).
>
>     Barry
>
>
> On Mon, 8 May 2006, Sh.M wrote:
>
> > Hi,
> >
> > If I want to check the maximum amount of memory PETSc has used during a
> > program run, is PetscMemoryGetMaximumUsage the function to use? I take
it a
> > call to this function will print out how much Process ID X has used, is
this
> > correct? So If I want to see the total maximum amount of memory used
during
> > a program run, each process should call this function and then I add
them to
> > get the total amount, correct?
> >
> > Thanks in advance.
> >
> > With best regards, Shaman Mahmoudi
> >
> >
>