For
>The matrix size is around 50000*50000, nnz is ~2000000

You may also try direct solver '-pc_type lu' either Petsc lu (sequential)
or mumps, or superlu_dist.
They may be faster than ilu(1).

Hong

On Mon, Dec 5, 2011 at 8:54 AM, Matthew Knepley <knepley at gmail.com> wrote:
> On Mon, Dec 5, 2011 at 8:46 AM, Debao Shao <Debao.Shao at brion.com> wrote:
>>
>> DA,
>>
>> 1, Will check_inode affect the runtime performance? For example, in my
>> case, there are such different logs:
>>
>> ???? [0] Mat_CheckInode(): Found 18602 nodes out of 18609 rows. Not using
>> Inode routines
>>
>> ???? [0] Mat_CheckInode(): Found 0 nodes of 0. Limit used: 5. Using Inode
>> routines
>>
>> ???? [0] Mat_CheckInode(): Found 14020 nodes out of 14020 rows. Not using
>> Inode routines
>
>
> This is intended to "discover" block structure. If you have it, MatMult
> should be faster.
>
>>
>> 2, Here is the log_summary, looks like PCSetup is big time-consuming
>> function, the method I?m using is ILU(1) & GMRES, may I improve it?
>>
>> ???? MatMult??????????? 30733 1.0 8.9553e+01 1.0 3.41e+10 1.0 0.0e+00
>> 0.0e+00 0.0e+00? 2? 4? 0? 0? 0?? 2? 4? 0? 0? 0?? 380
>>
>> ???? MatMultAdd????????? 9552 1.0 6.6610e+00 1.0 2.42e+09 1.0 0.0e+00
>> 0.0e+00 0.0e+00? 0? 0? 0? 0? 0?? 0? 0? 0? 0? 0?? 363
>>
>> ???? MatSolve?????????? 36236 1.0 2.4699e+02 1.0 9.44e+10 1.0 0.0e+00
>> 0.0e+00 0.0e+00? 6 10? 0? 0? 0?? 6 10? 0? 0? 0?? 382
>>
>> ???? MatLUFactorNum????? 2838 1.0 2.4328e+03 1.0 7.65e+11 1.0 0.0e+00
>> 0.0e+00 0.0e+00 61 85? 0? 0? 0? 61 85? 0? 0? 0?? 315
>>
>> ???? MatILUFactorSym????? 173 1.0 1.3486e+02 1.0 0.00e+00 0.0 0.0e+00
>> 0.0e+00 0.0e+00? 3? 0? 0? 0? 0?? 3? 0? 0? 0? 0???? 0
>>
>> ???? MatAssemblyBegin??? 5787 1.0 2.0547e-03 1.0 0.00e+00 0.0 0.0e+00
>> 0.0e+00 0.0e+00? 0? 0? 0? 0? 0?? 0? 0? 0? 0? 0???? 0
>>
>> ???? MatAssemblyEnd????? 5787 1.0 5.3559e+00 1.0 0.00e+00 0.0 0.0e+00
>> 0.0e+00 0.0e+00? 0? 0? 0? 0? 0?? 0? 0? 0? 0? 0???? 0
>>
>> ???? KSPGMRESOrthog???? 30679 1.0 5.5968e+00 1.0 4.06e+09 1.0 0.0e+00
>> 0.0e+00 0.0e+00? 0? 0? 0? 0? 0?? 0? 0? 0? 0? 0?? 725
>>
>> ???? KSPSetup??????????? 2838 1.0 1.8219e-02 1.0 0.00e+00 0.0 0.0e+00
>> 0.0e+00 0.0e+00? 0? 0? 0? 0? 0?? 0? 0? 0? 0? 0???? 0
>>
>> ???? KSPSolve??????????? 5503 1.0 2.9136e+03 1.0 8.99e+11 1.0 0.0e+00
>> 0.0e+00 0.0e+00 73100? 0? 0? 0? 73100? 0? 0? 0?? 308
>>
>> ???? PCSetUp???????????? 2838 1.0 2.5682e+03 1.0 7.65e+11 1.0 0.0e+00
>> 0.0e+00 0.0e+00 64 85? 0? 0? 0? 64 85? 0? 0? 0?? 298
>>
>> ???? PCApply??????????? 36236 1.0 2.4709e+02 1.0 9.44e+10 1.0 0.0e+00
>> 0.0e+00 0.0e+00? 6 10? 0? 0? 0?? 6 10? 0? 0? 0?? 382
>>
>> The matrix size is around 50000*50000, nnz is ~2000000
>
>
> ILU is expensive, and levels make it much more expensive. Maybe try AMG?
>>
>> 3, Will the fill of ilu affect the runtime performance?
>>
>> ???? [0] MatILUFactorSymbolic_SeqAIJ(): Reallocs 0 Fill ratio:given 1
>> needed 1.11111
>>
>> ???? [0] MatILUFactorSymbolic_SeqAIJ(): Reallocs 1 Fill ratio:given 1
>> needed 5.05
>>
>> ???? [0] MatILUFactorSymbolic_SeqAIJ(): Reallocs 1 Fill ratio:given 1
>> needed 8.3410
>>
>> How to set a proper value for fill, >8?
>
>
> http://www.mcs.anl.gov/petsc/petsc-dev/docs/manualpages/PC/PCFactorSetFill.html
>
> Use -pc_factor_fill
>
> ? Matt
>
>>
>> Thanks,
>>
>> Debao
>>
>>
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