Question about memory used by PetsC Objects
Laurent Nguyen
laurent.nguyen at idris.fr
Fri Apr 13 09:18:11 CDT 2007
Yes, I've tested the argument -memory_info. I've seen the memory given
to me is the same memory given by a PetscMemoryGetCurrentUsage() before
PetscFinalize(). I didn't know it was the same ^^.
It is not the memory I need. I would like to have the real memory used
by my program (It is a little difficult to explain clearly): for
example, if I create 2 vectors of size 100, the program is consuming
2*8*100 bytes. But later, when I destroy only 1 vector, the programs is
consuming 1*8*100 bytes. This is this kind of information that I need
(more precisely, the max). I tell you that because, in my context of
computation, I've only 1.5Go of memory per processors. And the memory
given by the argument -memory_info was 2.4Go. So I was perplex about
that. But now I understand how your function is running.
But thanks to yours functions, I can now better manage the memory of my
objects!
Regards,
**************************************
NGUYEN Anh-Khai Laurent
Equipe Support Utilisateur
Email : laurent.nguyen at idris.fr
Tél : 01.69.35.85.66
Adresse : IDRIS - Institut du Développement et des Ressources en
Informatique Scientifique
CNRS
Batiment 506
BP 167
F - 91403 ORSAY Cedex
Site Web : http://www.idris.fr
**************************************
Matthew Knepley a écrit :
> On 4/13/07, Laurent Nguyen <laurent.nguyen at idris.fr> wrote:
>> Barry,
>>
>> I thank you for your help. So I tried to apply the functions. It seems
>> that PetscMemoryGetCurrentUsage() gives the total amount of memory
>> allocated at the point of the program where it is placed. But, if a
>> object is deallocated, PetscMemoryGetCurrentUsage() doesn't take it.
>>
>> I would like to try PetscMemoryGetMaximumUsage() at the end of the
>> program hoping it gives me the maximum memory used by my program but
>> there are problems. When I put PetscMemoryGetMaximumUsage(), I've this
>> error at the execution:
>>
>> [0]PETSC ERROR: --------------------- Error Message
>> ------------------------------------
>> [0]PETSC ERROR: Object is in wrong state!
>> [0]PETSC ERROR: To use this function you must first call
>> PetscMemorySetGetMaximumUsage()!
>>
>> So I put PetscMemorySetGetMaximumUsage() before, but at linking, it
>> didn't find PetscMemorySetGetMaximumUsage in the petsc libraries. I
>> thought I made a bad install but when I tried on another machine, I've
>> the same problem.
>
> The function is definitely there (check src/sys/memory/mem.c). You can try
> a short test:
>
> cd src/ksp/ksp/examples/tutorials
> make ex2
> ./ex2 -memory_info
> ./ex2 -malloc_log
>
> Also, I have fixed the specific logging errors you pointed out in the dev
> copy, but we are doing a code review to make sure no other omissions
> are lurking.
>
> Matt
>
>> Best regards,
>>
>> **************************************
>> NGUYEN Anh-Khai Laurent
>> Equipe Support Utilisateur
>>
>> Email : laurent.nguyen at idris.fr
>> Tél : 01.69.35.85.66
>> Adresse : IDRIS - Institut du Développement et des Ressources en
>> Informatique Scientifique
>> CNRS
>> Batiment 506
>> BP 167
>> F - 91403 ORSAY Cedex
>> Site Web : http://www.idris.fr
>> **************************************
>>
>> Barry Smith a écrit :
>> > Laurent,
>> >
>> > The memory usage printed with -log_summary is not correct.
>> > Much of the memory used is not printed out.
>> >
>> > You can use PetscMemoryGetCurrentUsage() and
>> PetscMemoryGetMaximumUsage()
>> > in your code before and after creating a filling in PETSc objects
>> > to see how much memory they are used. You can also use
>> PetscMallocDump()
>> > at any point to see exactly where in PETSc and how much all of PETSc's
>> > memory was allocated.
>> >
>> > Barry
>> >
>> >
>> > On Thu, 12 Apr 2007, Laurent Nguyen wrote:
>> >
>> >> Hi,
>> >>
>> >> I'm a Petsc user, but I'm beginning to use petsc in a supercomputation
>> >> context. So, I'm trying parallel versions of my old mono-processed
>> programs.
>> >> But I've some difficulties to determine how much memory my program
>> use. (I
>> >> give a little example). In this example on one processor (with
>> these command
>> >> line arguments: -mat_type mpiaij -pc_type none -log_summary), I
>> created one
>> >> mpiaij matrix (size = 500*500) and two vectors (size = 500). I've this
>> >> information from output:
>> >>
>> >> Matrix Object:
>> >> type=mpiaij, rows=250000, cols=250000
>> >> total: nonzeros=749996, allocated nonzeros=1750000
>> >>
>> >> To me, there is an array of 1750000 double precision number of 8
>> bytes =
>> >> 14000000 bytes (14Mo).
>> >>
>> >> Same for vectors: 2*8*250000 = 4 Mo
>> >>
>> >> But in the log summary, I've:
>> >>
>> >> Memory usage is given in bytes:
>> >>
>> >> Object Type Creations Destructions Memory
>> Descendants' Mem.
>> >>
>> >> --- Event Stage 0: Main Stage
>> >>
>> >> Viewer 1 1 0 0
>> >> Index Set 2 2 672 0
>> >> Map 16 16 4992 0
>> >> Vec 10 10 2006576 0
>> >> Vec Scatter 1 1 0 0
>> >> Matrix 3 3 1068 0
>> >> Krylov Solver 1 1 17208 0
>> >> Preconditioner 1 1 0 0
>> >> =============================================================
>> >>
>> >> I don't understand this output...If you have some documentation
>> about how
>> >> Petsc deals with memory or if you can explain, I would be very
>> interested.
>> >>
>> >> This is a problem because I'm working on IBM SP4, and I've
>> limitations of
>> >> memory (700mb for data and 700mb for stack). I think the objects
>> created by
>> >> Petsc is created in the stack memory, but as I cannot determine
>> exactly the
>> >> memory usage, I cannot verify.
>> >>
>> >> Thank you for your advices,
>> >>
>> >> Best regards
>> >>
>> >>
>> >
>> >
>>
>>
>
>
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