[petsc-dev] asm / gasm

[Barry Smith]

> On Jun 22, 2016, at 10:20 PM, Mark Adams <mfadams at lbl.gov> wrote:
> 
>> 
>> No joke, Amneet found that PCASM with lots of small subdomains was spending a ton of time in view calls.
> 
> (And, of course, Barry fixed it by adding this configure flag --- thanks Barry!)
> 
> Note that it does not matter whether you use view or not.
> 
> Oh wow. So no view with ASM,
> 
> Garth, you will need to configure with '--with-viewfromoptions=0'

  Not really, first we make sure it runs correctly and only then do we optimize. 

  Please send me the arguments for the crash case with gasm so I can debug it.

   Thanks

  Barry
>  
> 
> -- Boyce
> 
>> 
>> -- Boyce
>> 
>>> I guess we should have a flag or not iterate over the blocks in ASMView ...
>>>  
>>> 
>>> -- Boyce
>>> 
>>>> 
>>>>   Barry
>>>> 
>>>>> On Jun 22, 2016, at 7:51 AM, Mark Adams <mfadams at lbl.gov> wrote:
>>>>> 
>>>>> I'm trying to get block smoothers to work for gamg.  We (Garth) tried this and got this error:
>>>>> 
>>>>> 
>>>>> - Another option is use '-pc_gamg_use_agg_gasm true' and use '-mg_levels_pc_type gasm'.
>>>>> 
>>>>> 
>>>>> Running in parallel, I get
>>>>> 
>>>>>     ** Max-trans not allowed because matrix is distributed
>>>>> ----
>>>>> 
>>>>> First, what is the difference between asm and gasm?
>>>>> 
>>>>> Second, I need to fix this to get block smoothers. This used to work.  Did we lose the capability to have blocks that span processor subdomains?
>>>>> 
>>>>> gamg only aggregates across processor subdomains within one layer, so maybe I could use one layer of overlap in some way?
>>>>> 
>>>>> Thanks,
>>>>> Mark
>>>>> 
>>> 
>>> 
> 
>