performance issue

[Jim Edwards]

On Thu, Aug 10, 2023 at 10:53 AM Wei-Keng Liao <wkliao at northwestern.edu>
wrote:

> From the file header dump you sent earlier, no PnetCDF hint is necessary.
>
> What MPI-IO hints are you using?
>
I am now using:
MPICH_MPIIO_HINTS=*:romio_cb_read=enable:romio_cb_write=enable:striping_factor=48:striping_unit=134217728

we explored the parameter space and this seems to be about the best for
this particular file.   But I think that there is still something
wrong at a low level and am working on trying to figure that out.


> One question. Did you delete the output file before each run?
>
> Yes




> Wei-keng
>
> On Aug 10, 2023, at 11:35 AM, Jim Edwards <jedwards at ucar.edu> wrote:
>
> We are having a lot of problems with darshan on our system - I'm working
> with the darshan developers to resolve.
>
> I am setting MPIIO hints - but I see that there are some hints specific to
> pnetcdf - do you have any recommendations?
>
> On Thu, Aug 10, 2023 at 10:15 AM Wei-Keng Liao <wkliao at northwestern.edu>
> wrote:
>
>> Hi, Jim
>>
>> FYI. Darshan now can capture the I/O activities of PnetCDF,
>> in addition to the already MPI-IO and POSIX-IO.
>>
>> Wei-keng
>>
>> On Aug 9, 2023, at 6:22 PM, Wei-Keng Liao <wkliao at northwestern.edu>
>> wrote:
>>
>> In that case, I have the E3SM-IO benchmark that has a fairly complicate
>> I/O
>> partitioning pattern. It used the decomposition maps generated from PIO.
>> https://github.com/Parallel-NetCDF/E3SM-IO
>> <https://urldefense.com/v3/__https://github.com/Parallel-NetCDF/E3SM-IO__;!!Dq0X2DkFhyF93HkjWTBQKhk!UJAnknjDPQWY43szbAutlokjDrSHyBOcTlhEOChqYtThxnr812hxwvb8aSmHcEPiNOxNdOUHZi9Z2fyXbg2j6JH1HTo$>
>>
>> Wei-keng
>>
>> On Aug 9, 2023, at 6:17 PM, Jim Edwards <jedwards at ucar.edu> wrote:
>>
>> I think that your example case is too simple - it's doing a simple block
>> decomposition.
>> In order to get the performance difference I am observing I need to do a
>> more complicated
>> mapping.   I will work on a program that reproduces the problem without
>> pio but it may take a
>> while.
>>
>>
>>
>>
>
> --
> Jim Edwards
>
> CESM Software Engineer
> National Center for Atmospheric Research
> Boulder, CO
>
>
>

-- 
Jim Edwards

CESM Software Engineer
National Center for Atmospheric Research
Boulder, CO
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