libmesh-users

[Libmesh-users] [RB] Time comparison between FE and RB methods

[<ss...@pu...>]

Hello, all.

 

I want to compare the computation time between FE and RB methods, so I
looked at "libMesh Performance."

Here, I used the "Avg Time with Sub" of "truth_solve()" as the FE solve time
in the RB offline stage.

And as the RB solve time, I used the "Avg Time with Sub" of "rb_solve()" in
the RB online stage.

But I don't know if these are right ways to compare computation times.

 

Please tell me which values are generally used to compare computation times
between FE and RB methods.

 

For reference, results of "libMesh Performance" in my codes are as follows.

(Offline stage)

 

libMesh Performance: Alive time=1702.12, Active time=1692.06

----------------------------------------------------------------------------
-----------------------------------

| Event                                                         nCalls
Total Time         Avg Time         Total Time       Avg Time
% of     Active Time       |

|
w/o Sub           w/o Sub           With Sub          With Sub        w/o S
With S            |

----------------------------------------------------------------------------
-----------------------------------

.
|

(skip)
|

.
|

| RBConstruction
|

|     add_scaled_matrix_and_vector()                63         16.6728
0.264648          37.1072           0.589003                0.99    2.19
|

|     clear()                                                 1
0.0356            0.035607         0.0356            0.035607
0.00    0.00                  |

|     compute_Fq_representor_innerprods()      1           0.0161
0.016134         2.9970            2.997019             0.00    0.18
|

|     compute_max_error_bound()                   17         0.0722
0.004249         201.1186         11.830503             0.00    11.89
|

|     enrich_RB_space()                                16         0.6050
0.037811         0.6050            0.037811            0.04    0.04
|

|     train_reduced_basis()                              1           0.0032
0.003184         1661.9738       1661.973753            0.00     98.22
|

|     truth_assembly()                                     16
40.6187           2.538670         40.6187           2.538670
2.40    2.40                 |

|     truth_solve()                                           16
0.0534              0.003335         92.7523           5.797018
0.00      5.48                 |

|     update_RB_system_matrices()                 16         41.3210
2.582562         41.3210           2.582562                2.44      2.44
|

|     update_residual_terms()                          16         1222.1235
76.382721       1323.1667         82.697919               72.23    78.20
|

.
|

(skip)
|

.
|

----------------------------------------------------------------------------
-----------------------------------

(Online stage)

 

libMesh Performance: Alive time=3.62904, Active time=2.99889  

----------------------------------------------------------------------------
-----------------------------------

| Event                                                         nCalls
Total Time         Avg Time         Total Time       Avg Time
% of     Active Time       |

|
w/o Sub           w/o Sub           With Sub          With Sub        w/o S
With S            |

----------------------------------------------------------------------------
-----------------------------------

.
|

(skip)
|

.
|

| RBEvaluation
|

|     clear()                                                   1
0.0002           0.000194         0.0002            0.000194
0.01     0.01                |

|     compute_residual_dual_norm()                1          0.1543
0.154302         0.1543            0.154302                5.15     5.15
|

|     legacy_read_offline_data_from_files()       1          0.0218
0.021824         0.0247            0.024672                0.73     0.82
|

|     rb_solve()                                              1
0.0002           0.000175         0.1545            0.154478
0.01     5.15                |

|     read_in_basis_functions()                        1          0.0000
0.000005         0.3755            0.375475                0.00     12.52
|

|     read_in_vectors_from_multiple_files()        1          0.0706
0.070551         0.3755            0.375469                2.35     12.52
|

|     resize_data_structures()                          1          0.0028
0.002847         0.0028            0.002847                0.09     0.09
|

.
|

(skip)
|

.
|

----------------------------------------------------------------------------
-----------------------------------

 

I look forward to your reply.

 

Thank you.

 

Regards,

SKang

 

Re: [Libmesh-users] [RB] Time comparison between FE and RB methods

[David K. <dav...@ak...>]

Hello,

Yes, you can use the "libMesh Performance" output to see how long each type
of solve took. To get an RB solve time I would normally do an "online
stage" solve and look at the timing info for "rb_solve". To get an FE solve
time, you can look at the average time of a truth_solve, that should be
fine.

Note that the speedup you observe generally depends a lot on the details of
the problem, and is generally larger for problems with large FE meshes
(especially in 3D).

Best,
David


On Fri, Jun 8, 2018 at 1:18 AM, <ss...@pu...> wrote:

> Hello, all.
>
>
>
> I want to compare the computation time between FE and RB methods, so I
> looked at "libMesh Performance."
>
> Here, I used the "Avg Time with Sub" of "truth_solve()" as the FE solve
> time
> in the RB offline stage.
>
> And as the RB solve time, I used the "Avg Time with Sub" of "rb_solve()" in
> the RB online stage.
>
> But I don't know if these are right ways to compare computation times.
>
>
>
> Please tell me which values are generally used to compare computation times
> between FE and RB methods.
>
>
>
> For reference, results of "libMesh Performance" in my codes are as follows.
>
> (Offline stage)
>
>
>
> libMesh Performance: Alive time=1702.12, Active time=1692.06
>
> ------------------------------------------------------------
> ----------------
> -----------------------------------
>
> | Event                                                         nCalls
> Total Time         Avg Time         Total Time       Avg Time
> % of     Active Time       |
>
> |
> w/o Sub           w/o Sub           With Sub          With Sub        w/o S
> With S            |
>
> ------------------------------------------------------------
> ----------------
> -----------------------------------
>
> .
> |
>
> (skip)
> |
>
> .
> |
>
> | RBConstruction
> |
>
> |     add_scaled_matrix_and_vector()                63         16.6728
> 0.264648          37.1072           0.589003                0.99    2.19
> |
>
> |     clear()                                                 1
> 0.0356            0.035607         0.0356            0.035607
> 0.00    0.00                  |
>
> |     compute_Fq_representor_innerprods()      1           0.0161
> 0.016134         2.9970            2.997019             0.00    0.18
> |
>
> |     compute_max_error_bound()                   17         0.0722
> 0.004249         201.1186         11.830503             0.00    11.89
> |
>
> |     enrich_RB_space()                                16         0.6050
> 0.037811         0.6050            0.037811            0.04    0.04
> |
>
> |     train_reduced_basis()                              1           0.0032
> 0.003184         1661.9738       1661.973753            0.00     98.22
> |
>
> |     truth_assembly()                                     16
> 40.6187           2.538670         40.6187           2.538670
> 2.40    2.40                 |
>
> |     truth_solve()                                           16
> 0.0534              0.003335         92.7523           5.797018
> 0.00      5.48                 |
>
> |     update_RB_system_matrices()                 16         41.3210
> 2.582562         41.3210           2.582562                2.44      2.44
> |
>
> |     update_residual_terms()                          16         1222.1235
> 76.382721       1323.1667         82.697919               72.23    78.20
> |
>
> .
> |
>
> (skip)
> |
>
> .
> |
>
> ------------------------------------------------------------
> ----------------
> -----------------------------------
>
> (Online stage)
>
>
>
> libMesh Performance: Alive time=3.62904, Active time=2.99889
>
> ------------------------------------------------------------
> ----------------
> -----------------------------------
>
> | Event                                                         nCalls
> Total Time         Avg Time         Total Time       Avg Time
> % of     Active Time       |
>
> |
> w/o Sub           w/o Sub           With Sub          With Sub        w/o S
> With S            |
>
> ------------------------------------------------------------
> ----------------
> -----------------------------------
>
> .
> |
>
> (skip)
> |
>
> .
> |
>
> | RBEvaluation
> |
>
> |     clear()                                                   1
> 0.0002           0.000194         0.0002            0.000194
> 0.01     0.01                |
>
> |     compute_residual_dual_norm()                1          0.1543
> 0.154302         0.1543            0.154302                5.15     5.15
> |
>
> |     legacy_read_offline_data_from_files()       1          0.0218
> 0.021824         0.0247            0.024672                0.73     0.82
> |
>
> |     rb_solve()                                              1
> 0.0002           0.000175         0.1545            0.154478
> 0.01     5.15                |
>
> |     read_in_basis_functions()                        1          0.0000
> 0.000005         0.3755            0.375475                0.00     12.52
> |
>
> |     read_in_vectors_from_multiple_files()        1          0.0706
> 0.070551         0.3755            0.375469                2.35     12.52
> |
>
> |     resize_data_structures()                          1          0.0028
> 0.002847         0.0028            0.002847                0.09     0.09
> |
>
> .
> |
>
> (skip)
> |
>
> .
> |
>
> ------------------------------------------------------------
> ----------------
> -----------------------------------
>
>
>
> I look forward to your reply.
>
>
>
> Thank you.
>
>
>
> Regards,
>
> SKang
>
>
>
> ------------------------------------------------------------
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