[petsc-users] block ILU(K) is slower than the point-wise version?
Jed Brown
jed at jedbrown.org
Tue Mar 7 16:16:48 CST 2017
Hong <hzhang at mcs.anl.gov> writes:
> Fande,
> Got it. Below are what I get:
Is Fande using ILU(0) or ILU(k)? (And I think it should be possible to
get a somewhat larger benefit.)
> petsc/src/ksp/ksp/examples/tutorials (master)
> $ ./ex10 -f0 binaryoutput -rhs 0 -mat_view ascii::ascii_info
> Mat Object: 1 MPI processes
> type: seqaij
> rows=8019, cols=8019, bs=11
> total: nonzeros=1890625, allocated nonzeros=1890625
> total number of mallocs used during MatSetValues calls =0
> using I-node routines: found 2187 nodes, limit used is 5
> Number of iterations = 3
> Residual norm 0.00200589
>
> -mat_type aij
> MatMult 4 1.0 8.3621e-03 1.0 1.51e+07 1.0 0.0e+00 0.0e+00
> 0.0e+00 6 7 0 0 0 7 7 0 0 0 1805
> MatSolve 4 1.0 8.3971e-03 1.0 1.51e+07 1.0 0.0e+00 0.0e+00
> 0.0e+00 6 7 0 0 0 7 7 0 0 0 1797
> MatLUFactorNum 1 1.0 8.6171e-02 1.0 1.80e+08 1.0 0.0e+00 0.0e+00
> 0.0e+00 57 85 0 0 0 70 85 0 0 0 2086
> MatILUFactorSym 1 1.0 1.4951e-02 1.0 0.00e+00 0.0 0.0e+00 0.0e+00
> 0.0e+00 10 0 0 0 0 12 0 0 0 0 0
>
> -mat_type baij
> MatMult 4 1.0 5.5540e-03 1.0 1.51e+07 1.0 0.0e+00 0.0e+00
> 0.0e+00 4 5 0 0 0 7 5 0 0 0 2718
> MatSolve 4 1.0 7.0803e-03 1.0 1.48e+07 1.0 0.0e+00 0.0e+00
> 0.0e+00 5 5 0 0 0 8 5 0 0 0 2086
> MatLUFactorNum 1 1.0 6.0118e-02 1.0 2.55e+08 1.0 0.0e+00 0.0e+00
> 0.0e+00 42 89 0 0 0 72 89 0 0 0 4241
> MatILUFactorSym 1 1.0 6.7251e-03 1.0 0.00e+00 0.0 0.0e+00 0.0e+00
> 0.0e+00 5 0 0 0 0 8 0 0 0 0 0
>
> I ran it on my macpro. baij is faster than aij in all routines.
>
> Hong
>
> On Tue, Mar 7, 2017 at 2:26 PM, Kong, Fande <fande.kong at inl.gov> wrote:
>
>> Uploaded to google drive, and sent you links in another email. Not sure if
>> it works or not.
>>
>> Fande,
>>
>> On Tue, Mar 7, 2017 at 12:29 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>>
>>>
>>> It is too big for email you can post it somewhere so we can download
>>> it.
>>>
>>>
>>>
>>> > On Mar 7, 2017, at 12:01 PM, Kong, Fande <fande.kong at inl.gov> wrote:
>>> >
>>> >
>>> >
>>> > On Tue, Mar 7, 2017 at 10:23 AM, Hong <hzhang at mcs.anl.gov> wrote:
>>> > I checked
>>> > MatILUFactorSymbolic_SeqBAIJ() and MatILUFactorSymbolic_SeqAIJ(),
>>> > they are virtually same. Why the version for BAIJ is so much slower?
>>> > I'll investigate it.
>>> >
>>> > Fande,
>>> > How large is your matrix? Is it possible to send us your matrix so I
>>> can test it?
>>> >
>>> > Thanks, Hong,
>>> >
>>> > It is a 3020875x3020875 matrix, and it is large. I can make a small one
>>> if you like, but not sure it will reproduce this issue or not.
>>> >
>>> > Fande,
>>> >
>>> >
>>> >
>>> > Hong
>>> >
>>> >
>>> > On Mon, Mar 6, 2017 at 9:08 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>>> >
>>> > Thanks. Even the symbolic is slower for BAIJ. I don't like that, it
>>> definitely should not be since it is (at least should be) doing a symbolic
>>> factorization on a symbolic matrix 1/11th the size!
>>> >
>>> > Keep us informed.
>>> >
>>> >
>>> >
>>> > > On Mar 6, 2017, at 5:44 PM, Kong, Fande <fande.kong at inl.gov> wrote:
>>> > >
>>> > > Thanks, Barry,
>>> > >
>>> > > Log info:
>>> > >
>>> > > AIJ:
>>> > >
>>> > > MatSolve 850 1.0 8.6543e+00 4.2 3.04e+09 1.8 0.0e+00
>>> 0.0e+00 0.0e+00 0 41 0 0 0 0 41 0 0 0 49594
>>> > > MatLUFactorNum 25 1.0 1.7622e+00 2.0 2.04e+09 2.1 0.0e+00
>>> 0.0e+00 0.0e+00 0 26 0 0 0 0 26 0 0 0 153394
>>> > > MatILUFactorSym 13 1.0 2.8002e-01 2.9 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
>>> > >
>>> > > BAIJ:
>>> > >
>>> > > MatSolve 826 1.0 1.3016e+01 1.7 1.42e+10 1.8 0.0e+00
>>> 0.0e+00 0.0e+00 1 29 0 0 0 1 29 0 0 0 154617
>>> > > MatLUFactorNum 25 1.0 1.5503e+01 2.0 3.55e+10 2.1 0.0e+00
>>> 0.0e+00 0.0e+00 1 67 0 0 0 1 67 0 0 0 303190
>>> > > MatILUFactorSym 13 1.0 5.7561e-01 1.8 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
>>> > >
>>> > > It looks like both MatSolve and MatLUFactorNum are slower.
>>> > >
>>> > > I will try your suggestions.
>>> > >
>>> > > Fande
>>> > >
>>> > > On Mon, Mar 6, 2017 at 4:14 PM, Barry Smith <bsmith at mcs.anl.gov>
>>> wrote:
>>> > >
>>> > > Note also that if the 11 by 11 blocks are actually sparse (and you
>>> don't store all the zeros in the blocks in the AIJ format) then then AIJ
>>> non-block factorization involves less floating point operations and less
>>> memory access so can be faster than the BAIJ format, depending on "how
>>> sparse" the blocks are. If you actually "fill in" the 11 by 11 blocks with
>>> AIJ (with zeros maybe in certain locations) then the above is not true.
>>> > >
>>> > >
>>> > > > On Mar 6, 2017, at 5:10 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>>> > > >
>>> > > >
>>> > > > This is because for block size 11 it is using calls to
>>> LAPACK/BLAS for the block operations instead of custom routines for that
>>> block size.
>>> > > >
>>> > > > Here is what you need to do. For a good sized case run both with
>>> -log_view and check the time spent in
>>> > > > MatLUFactorNumeric, MatLUFactorSymbolic and in MatSolve for AIJ and
>>> BAIJ. If they have a different number of function calls then divide by the
>>> function call count to determine the time per function call.
>>> > > >
>>> > > > This will tell you which routine needs to be optimized first
>>> either MatLUFactorNumeric or MatSolve. My guess is MatSolve.
>>> > > >
>>> > > > So edit src/mat/impls/baij/seq/baijsolvnat.c and copy the
>>> function MatSolve_SeqBAIJ_15_NaturalOrdering_ver1() to a new function
>>> MatSolve_SeqBAIJ_11_NaturalOrdering_ver1. Edit the new function for the
>>> block size of 11.
>>> > > >
>>> > > > Now edit MatLUFactorNumeric_SeqBAIJ_N() so that if block size is
>>> 11 it uses the new routine something like.
>>> > > >
>>> > > > if (both_identity) {
>>> > > > if (b->bs == 11)
>>> > > > C->ops->solve = MatSolve_SeqBAIJ_11_NaturalOrdering_ver1;
>>> > > > } else {
>>> > > > C->ops->solve = MatSolve_SeqBAIJ_N_NaturalOrdering;
>>> > > > }
>>> > > >
>>> > > > Rerun and look at the new -log_view. Send all three -log_view to
>>> use at this point. If this optimization helps and now
>>> > > > MatLUFactorNumeric is the time sink you can do the process to
>>> MatLUFactorNumeric_SeqBAIJ_15_NaturalOrdering() to make an 11 size block
>>> custom version.
>>> > > >
>>> > > > Barry
>>> > > >
>>> > > >> On Mar 6, 2017, at 4:32 PM, Kong, Fande <fande.kong at inl.gov>
>>> wrote:
>>> > > >>
>>> > > >>
>>> > > >>
>>> > > >> On Mon, Mar 6, 2017 at 3:27 PM, Patrick Sanan <
>>> patrick.sanan at gmail.com> wrote:
>>> > > >> On Mon, Mar 6, 2017 at 1:48 PM, Kong, Fande <fande.kong at inl.gov>
>>> wrote:
>>> > > >>> Hi All,
>>> > > >>>
>>> > > >>> I am solving a nonlinear system whose Jacobian matrix has a block
>>> structure.
>>> > > >>> More precisely, there is a mesh, and for each vertex there are 11
>>> variables
>>> > > >>> associated with it. I am using BAIJ.
>>> > > >>>
>>> > > >>> I thought block ILU(k) should be more efficient than the
>>> point-wise ILU(k).
>>> > > >>> After some numerical experiments, I found that the block ILU(K)
>>> is much
>>> > > >>> slower than the point-wise version.
>>> > > >> Do you mean that it takes more iterations to converge, or that the
>>> > > >> time per iteration is greater, or both?
>>> > > >>
>>> > > >> The number of iterations is very similar, but the timer per
>>> iteration is greater.
>>> > > >>
>>> > > >>
>>> > > >>>
>>> > > >>> Any thoughts?
>>> > > >>>
>>> > > >>> Fande,
>>> > > >>
>>> > > >
>>> > >
>>> > >
>>> >
>>> >
>>> >
>>>
>>>
>>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 832 bytes
Desc: not available
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20170307/2cd3637f/attachment-0001.pgp>
More information about the petsc-users
mailing list