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

[Pierre Jolivet]

> On 22 Apr 2021, at 7:45 PM, Barry Smith <bsmith at petsc.dev> wrote:
> 
> 
>   It would be straightforward to add an option to -info to output only from a particular MPI_COMM_WORLD global rank.
> 
>   Maybe an extra :rank at the end of the info options?
> 
>   Open 128k files is nuts.

It is what it is, I’ve made peace with the fact that I can’t expect any meaningful timings for large runs when this option is on.
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 <mailto: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 <mailto:pierre at joliv.et>> wrote:
>> 
>> 
>>> On 22 Apr 2021, at 5:33 PM, Jacob Faibussowitsch <jacob.fai at gmail.com <mailto: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 <mailto:mfadams at lbl.gov>> wrote:
>>>> 
>>>> Can I make -info only print from one process?
>>>> Mark
>>> 
>> 
> 

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