[CIG-SHORT] Understanding the memory usage

[Brad Aagaard]

Hongfeng,

The memory usage in the log summary is for PETSc objects. It does not 
include any Sieve or PyLith objects. For simulations with explicit time 
stepping very few PETSc objects are created (mainly for output).

Regards,
Brad


On 7/31/12 1:00 PM, Hongfeng Yang wrote:
> Hi all,
>
> After a simulation, I read the memory usage summary from the running
> output as the following:
>
> Memory usage is given in bytes:
>
> Object Type          Creations   Destructions     Memory Descendants' Mem.
> Reports information only for process 0.
>
> --- Event Stage 0: Main Stage
>
>                 Vector     0             30     14829024     0
>         Vector Scatter     0              6         6216     0
>                 Viewer     1              0            0     0
>
> --- Event Stage 1: Meshing
>
>
> --- Event Stage 2: Setup
>
>                 Vector    76             51      9908736     0
>         Vector Scatter    12              8         8288     0
>                 Viewer     8              3         2040     0
>              Index Set    24             24        17856     0
>
> --- Event Stage 3: Reform Jacobian
>
>
> --- Event Stage 4: Reform Residual
>
>
> --- Event Stage 5: Unknown
>
>
> --- Event Stage 6: Prestep
>
>
> --- Event Stage 7: Step
>
>                 Vector     2              0            0     0
>
> --- Event Stage 8: Poststep
>
>                 Vector    20             12      8623544     0
>         Vector Scatter     4              2         2072     0
>              Index Set     8              8         5952     0
>
> --- Event Stage 9: Finalize
>
>                 Vector     0              5         7520     0
>                 Viewer     0              5         3400     0
>
> The accumulated memory usage is about 34 M according to the above info.
> However, looking up the memory usage from "top" on my machine, every
> single run takes about 3% of the total memory, which is 24 G. That gives
> an estimation of 720 M per core, a big difference from the Pylith output.
>
> Which one really tells me the real memory usage of Pylith? Or am I
> reading something wrong?
>
> Thanks,
>
> Hongfeng
>
>
>