[petsc-dev] -info from just one process?

[Mark Adams]

I did not know about  -log_trace.
Good to know,
Thanks

On Fri, Apr 23, 2021 at 8:19 AM Stefano Zampini <stefano.zampini at gmail.com>
wrote:

>
>
>
>> I'm not talking about timings, I am talking about seeing where a code
>> dies.
>>
>
> When codes die within the MPI implementation is basically impossible to
> provide a backtrace from PETSc, but the MPI implementation may offer some
> verbose messaging.
> If this happens quite early in the code (and I presume here we are failing
> somewhere in the 1-to-all pattern when distributing the plex data
> structure) running with -log_trace may get you some insight on where this
> is happening  (provided that the offending PETSc routine calls
> LogEventBegin/End)
>
> In my experience, the sad story is that when there are software
> vendor failures with a large number of processes, I haven't found anything
> more efficient than a few bisection steps with good old printfs....
>
>
>>
>>
>>> As a side note, one would expect that this kind of behavior is
>>> consistent across the library.
>>> But in fact, it isn’t. If you do something like -sub_ksp_view_pmat file
>>> with, for example, DD preconditioners, you end up with a single file with
>>> all local matrices scrambled in.
>>> It would be nice to have the same logic, i.e., file.%p, and be able to
>>> filter ranks that actually print to file like you suggest.
>>> These kind of options are less critical than -info so I can just insert
>>> them in the option database after initialization, if rank == view_this_rank
>>> PetscOptionsInsertString(), but doing that using command line arguments
>>> would be easier and more elegant, IMO.
>>>
>>> Thanks,
>>> Pierre
>>>
>>>   Barry
>>>
>>> On Apr 22, 2021, at 11:14 AM, Mark Adams <mfadams at lbl.gov> wrote:
>>>
>>> OK, so -info out.%p would do what I asked. Alas, what I really need it
>>> to reduce the output with 128K processes.
>>> Thanks,
>>>
>>> On Thu, Apr 22, 2021 at 11:54 AM Pierre Jolivet <pierre at joliv.et> wrote:
>>>
>>>>
>>>>
>>>> On 22 Apr 2021, at 5:33 PM, Jacob Faibussowitsch <jacob.fai at gmail.com>
>>>> wrote:
>>>>
>>>> Not out of the box no. There is -info ::self which makes info only
>>>> print from calls made on PETSC_COMM_SELF, but I don’t think that’s what you
>>>> want. Best advice would be to print to a file and grep the file for any
>>>> lines starting with the rank number you want.
>>>>
>>>>
>>>> There is no need for grep, IMHO, just do -info file and then open
>>>> file.%p
>>>>
>>>> Thanks,
>>>> Pierre
>>>>
>>>> Best regards,
>>>>
>>>> Jacob Faibussowitsch
>>>> (Jacob Fai - booss - oh - vitch)
>>>>
>>>> On Apr 22, 2021, at 10:16, Mark Adams <mfadams at lbl.gov> wrote:
>>>>
>>>> Can I make -info only print from one process?
>>>> Mark
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>
> --
> Stefano
>
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