[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Question about memory used by PetsC Objects

On 4/13/07, Laurent Nguyen <laurent.nguyen@xxxxxxxx> 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@xxxxxxxx
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
>>
>>
>
>




--
The government saving money is like me spilling beer. It happens, but
never on purpose.