[petsc-dev] making DA more light weight

[Jed Brown]

Barry Smith <bsmith at mcs.anl.gov> writes:

> On May 15, 2014, at 5:42 PM, Jed Brown <jed at jedbrown.org> wrote:
>
>> Barry Smith <bsmith at mcs.anl.gov> writes:
>> 
>>>  I suggest the following:  
>>> 
>>>    ISLocalToGlobalCreate() takes a block size. 
>>> 
>>>    ISLocalToGlobalApply() will then do the integer arithmetic if bs > 1
>>> 
>>>    ISLocalToGlobalApplyBlock() will just use the given indices 
>>> 
>>>   Then Mat/VecSetLocalToGlobal() will only have one mapping and DMDACreate() will only create the block version 
>> 
>> That's what I meant in my other mail (rationalizing that integer
>> division should not ruin performance; needs to be tested).
>
>     Yes I know it is what you said, I was just laying out in more detail the API changes.

Perfect.

>>  I think this
>> is worthwhile and not hard, but it's small fish compared to VecScatter,
>> which requires several times as much memory.  
>
>     Not true
>
>> See my other mail with
>> full stack traces for each large allocation.
>
>     See my other email where I explained that since you ran in the debugger on one process you got very different results then you would get on two processes.

Not true, it was a 2-process run.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 835 bytes
Desc: not available
URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20140515/16b365b3/attachment.sig>