Re: [Libmesh-users] How long does the system assembling need?

[Shengli X. <she...@gm...>]

2008/7/30 Roy Stogner <ro...@st...>

>
> On Wed, 30 Jul 2008, Shengli Xu wrote:
>
>  But in next iteration the refinement level is 2, The process of system
>> assembling is very very slowly. It took more than 12 hours when only
>> assembled 30000 elements. The system and mesh information is :
>>
>
>    n_dofs()=253785
>>
>
>  Is the system too large for only one processor?
>>
>
> Large enough that you can't quickly solve many time steps on one
> processor, maybe... but large enough that one assembly should take 12
> hours?  Definitely not.  There's some sort of bug here.  If you could
> any more specific profiling information, it would help.


Roy, Could you tell me what specific profiling information should be
gotten?  I have to solve this problem.

The only culprit I've heard of that can destroy your assembly speed is if
> you
> try to assemble a bunch of matrices with entries outside PETSc's
> precalculated sparsity pattern, but before we figure out why that
> might be happening to you it would be a good idea to verify that
> that's what's happening.
> ---
> Roy
>



-- 
Yours Sincerely
Shengli Xu