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Je vois des résultats étranges de profilage avec gcc -pg et gprof.mauvais résultats gprof avec gcc -Ofast -pg
Je ne trouve pas de moyen de reproduction meilleur/plus petit, donc je suis en train de lier le code réel où je vois le problème.
J'utilise le code here, la construction gprof résultats de profilage avec make prof
Je remarque plusieurs erreurs, principalement:
- Une fonction
shape_stream_testqui ne devrait jamais même être appelé est présentée comme étant appelée fortement parai_best_move_recet prenant jusqu'à 15% du temps d'exécution total en temps libre - Autres fonctions légitimement appelé par
ai_best_move_reccommegrid_block_remove,grid_cpy,grid_newne même pas montrer que les enfants
Statistiques prof Actual:
Flat profile:
Each sample counts as 0.01 seconds.
% cumulative self self total
time seconds seconds calls ms/call ms/call name
53.92 4.00 4.00 4231936 0.00 0.00 grid_eval
13.62 5.01 1.01 4467368 0.00 0.00 shape_stream_test
6.88 5.52 0.51 4690742 0.00 0.00 grid_block_center_top
6.07 5.97 0.45 4521016 0.00 0.00 grid_block_valid
5.80 6.40 0.43 4467368 0.00 0.00 grid_block_add
3.37 6.65 0.25 4467368 0.00 0.00 grid_block_drop
2.02 6.80 0.15 35 4.29 209.20 ai_best_move_rec
1.95 6.95 0.15 235469 0.00 0.00 grid_init
1.75 7.08 0.13 9212461 0.00 0.00 block_extreme
1.48 7.19 0.11 4467402 0.00 0.00 block_move
0.94 7.26 0.07 1654899 0.00 0.00 block_get
0.54 7.30 0.04 block_crust_get
0.40 7.33 0.03 grid_block_set_color
0.27 7.35 0.02 4467368 0.00 0.00 grid_block_remove
0.27 7.37 0.02 235501 0.00 0.00 block_new
0.27 7.39 0.02 grid_block_intersects
0.20 7.40 0.02 235469 0.00 0.00 grid_new
0.13 7.41 0.01 235467 0.00 0.00 shape_stream_peek
0.13 7.42 0.01 drop_amount
0.00 7.42 0.00 621 0.00 0.00 grid_clear_lines
0.00 7.42 0.00 587 0.00 0.00 grid_cpy
0.00 7.42 0.00 35 0.00 0.00 grid_print
0.00 7.42 0.00 34 0.00 0.00 block_init
0.00 7.42 0.00 34 0.00 0.00 block_print
0.00 7.42 0.00 34 0.00 0.00 game_move_print
0.00 7.42 0.00 34 0.00 0.00 grid_apply_moves
0.00 7.42 0.00 34 0.00 0.00 shape_stream_pop
0.00 7.42 0.00 7 0.00 0.00 shape_new
0.00 7.42 0.00 1 0.00 0.00 shape_stream_new
% the percentage of the total running time of the
time program used by this function.
cumulative a running sum of the number of seconds accounted
seconds for by this function and those listed above it.
self the number of seconds accounted for by this
seconds function alone. This is the major sort for this
listing.
calls the number of times this function was invoked, if
this function is profiled, else blank.
self the average number of milliseconds spent in this
ms/call function per call, if this function is profiled,
else blank.
total the average number of milliseconds spent in this
ms/call function and its descendents per call, if this
function is profiled, else blank.
name the name of the function. This is the minor sort
for this listing. The index shows the location of
the function in the gprof listing. If the index is
in parenthesis it shows where it would appear in
the gprof listing if it were to be printed.
Copyright (C) 2012-2014 Free Software Foundation, Inc.
Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.
Call graph (explanation follows)
granularity: each sample hit covers 2 byte(s) for 0.13% of 7.42 seconds
index % time self children called name
<spontaneous>
[1] 98.7 0.00 7.32 ai_test [1]
0.15 7.17 35/35 ai_best_move_rec [2]
0.00 0.00 34/34 grid_apply_moves [21]
0.00 0.00 2/235469 grid_new [9]
0.00 0.00 35/35 grid_print [24]
0.00 0.00 34/34 game_move_print [27]
0.00 0.00 34/34 shape_stream_pop [28]
0.00 0.00 1/1 shape_stream_new [30]
-----------------------------------------------
235432 ai_best_move_rec [2]
0.15 7.17 35/35 ai_test [1]
[2] 98.7 0.15 7.17 35+235432 ai_best_move_rec [2]
4.00 0.00 4231936/4231936 grid_eval [3]
1.01 0.00 4467368/4467368 shape_stream_test [4]
0.51 0.11 4690742/4690742 grid_block_center_top [5]
0.45 0.09 4521016/4521016 grid_block_valid [6]
0.43 0.00 4467368/4467368 grid_block_add [7]
0.25 0.00 4467368/4467368 grid_block_drop [8]
0.02 0.15 235467/235469 grid_new [9]
0.11 0.00 4467368/4467402 block_move [12]
0.02 0.00 4467368/4467368 grid_block_remove [16]
0.02 0.00 235467/235501 block_new [17]
0.01 0.00 235467/235467 shape_stream_peek [19]
0.00 0.00 587/587 grid_cpy [23]
0.00 0.00 587/621 grid_clear_lines [22]
235432 ai_best_move_rec [2]
-----------------------------------------------
4.00 0.00 4231936/4231936 ai_best_move_rec [2]
[3] 53.9 4.00 0.00 4231936 grid_eval [3]
-----------------------------------------------
1.01 0.00 4467368/4467368 ai_best_move_rec [2]
[4] 13.6 1.01 0.00 4467368 shape_stream_test [4]
-----------------------------------------------
0.51 0.11 4690742/4690742 ai_best_move_rec [2]
[5] 8.4 0.51 0.11 4690742 grid_block_center_top [5]
0.07 0.00 4690742/9212461 block_extreme [11]
0.04 0.00 1056160/1654899 block_get [13]
-----------------------------------------------
0.45 0.09 4521016/4521016 ai_best_move_rec [2]
[6] 7.3 0.45 0.09 4521016 grid_block_valid [6]
0.06 0.00 4521016/9212461 block_extreme [11]
0.03 0.00 598739/1654899 block_get [13]
-----------------------------------------------
0.43 0.00 4467368/4467368 ai_best_move_rec [2]
[7] 5.8 0.43 0.00 4467368 grid_block_add [7]
-----------------------------------------------
0.25 0.00 4467368/4467368 ai_best_move_rec [2]
[8] 3.4 0.25 0.00 4467368 grid_block_drop [8]
0.00 0.00 635/9212461 block_extreme [11]
-----------------------------------------------
0.00 0.00 2/235469 ai_test [1]
0.02 0.15 235467/235469 ai_best_move_rec [2]
[9] 2.2 0.02 0.15 235469 grid_new [9]
0.15 0.00 235469/235469 grid_init [10]
-----------------------------------------------
0.15 0.00 235469/235469 grid_new [9]
[10] 2.0 0.15 0.00 235469 grid_init [10]
-----------------------------------------------
0.00 0.00 68/9212461 grid_apply_moves [21]
0.00 0.00 635/9212461 grid_block_drop [8]
0.06 0.00 4521016/9212461 grid_block_valid [6]
0.07 0.00 4690742/9212461 grid_block_center_top [5]
[11] 1.8 0.13 0.00 9212461 block_extreme [11]
-----------------------------------------------
0.00 0.00 34/4467402 grid_apply_moves [21]
0.11 0.00 4467368/4467402 ai_best_move_rec [2]
[12] 1.5 0.11 0.00 4467402 block_move [12]
-----------------------------------------------
0.03 0.00 598739/1654899 grid_block_valid [6]
0.04 0.00 1056160/1654899 grid_block_center_top [5]
[13] 0.9 0.07 0.00 1654899 block_get [13]
-----------------------------------------------
<spontaneous>
[14] 0.5 0.04 0.00 block_crust_get [14]
-----------------------------------------------
<spontaneous>
[15] 0.4 0.03 0.00 grid_block_set_color [15]
-----------------------------------------------
0.02 0.00 4467368/4467368 ai_best_move_rec [2]
[16] 0.3 0.02 0.00 4467368 grid_block_remove [16]
-----------------------------------------------
0.00 0.00 34/235501 grid_apply_moves [21]
0.02 0.00 235467/235501 ai_best_move_rec [2]
[17] 0.3 0.02 0.00 235501 block_new [17]
-----------------------------------------------
<spontaneous>
[18] 0.3 0.02 0.00 grid_block_intersects [18]
-----------------------------------------------
0.01 0.00 235467/235467 ai_best_move_rec [2]
[19] 0.1 0.01 0.00 235467 shape_stream_peek [19]
-----------------------------------------------
<spontaneous>
[20] 0.1 0.01 0.00 drop_amount [20]
-----------------------------------------------
0.00 0.00 34/34 ai_test [1]
[21] 0.0 0.00 0.00 34 grid_apply_moves [21]
0.00 0.00 34/235501 block_new [17]
0.00 0.00 68/9212461 block_extreme [11]
0.00 0.00 34/4467402 block_move [12]
0.00 0.00 34/34 block_init [25]
0.00 0.00 34/621 grid_clear_lines [22]
-----------------------------------------------
0.00 0.00 34/621 grid_apply_moves [21]
0.00 0.00 587/621 ai_best_move_rec [2]
[22] 0.0 0.00 0.00 621 grid_clear_lines [22]
-----------------------------------------------
0.00 0.00 587/587 ai_best_move_rec [2]
[23] 0.0 0.00 0.00 587 grid_cpy [23]
-----------------------------------------------
0.00 0.00 35/35 ai_test [1]
[24] 0.0 0.00 0.00 35 grid_print [24]
-----------------------------------------------
0.00 0.00 34/34 grid_apply_moves [21]
[25] 0.0 0.00 0.00 34 block_init [25]
-----------------------------------------------
0.00 0.00 34/34 game_move_print [27]
[26] 0.0 0.00 0.00 34 block_print [26]
-----------------------------------------------
0.00 0.00 34/34 ai_test [1]
[27] 0.0 0.00 0.00 34 game_move_print [27]
0.00 0.00 34/34 block_print [26]
-----------------------------------------------
0.00 0.00 34/34 ai_test [1]
[28] 0.0 0.00 0.00 34 shape_stream_pop [28]
-----------------------------------------------
0.00 0.00 7/7 shapes_read [68]
[29] 0.0 0.00 0.00 7 shape_new [29]
-----------------------------------------------
0.00 0.00 1/1 ai_test [1]
[30] 0.0 0.00 0.00 1 shape_stream_new [30]
-----------------------------------------------
This table describes the call tree of the program, and was sorted by
the total amount of time spent in each function and its children.
Each entry in this table consists of several lines. The line with the
index number at the left hand margin lists the current function.
The lines above it list the functions that called this function,
and the lines below it list the functions this one called.
This line lists:
index A unique number given to each element of the table.
Index numbers are sorted numerically.
The index number is printed next to every function name so
it is easier to look up where the function is in the table.
% time This is the percentage of the `total' time that was spent
in this function and its children. Note that due to
different viewpoints, functions excluded by options, etc,
these numbers will NOT add up to 100%.
self This is the total amount of time spent in this function.
children This is the total amount of time propagated into this
function by its children.
called This is the number of times the function was called.
If the function called itself recursively, the number
only includes non-recursive calls, and is followed by
a `+' and the number of recursive calls.
name The name of the current function. The index number is
printed after it. If the function is a member of a
cycle, the cycle number is printed between the
function's name and the index number.
For the function's parents, the fields have the following meanings:
self This is the amount of time that was propagated directly
from the function into this parent.
children This is the amount of time that was propagated from
the function's children into this parent.
called This is the number of times this parent called the
function `/' the total number of times the function
was called. Recursive calls to the function are not
included in the number after the `/'.
name This is the name of the parent. The parent's index
number is printed after it. If the parent is a
member of a cycle, the cycle number is printed between
the name and the index number.
If the parents of the function cannot be determined, the word
`<spontaneous>' is printed in the `name' field, and all the other
fields are blank.
For the function's children, the fields have the following meanings:
self This is the amount of time that was propagated directly
from the child into the function.
children This is the amount of time that was propagated from the
child's children to the function.
called This is the number of times the function called
this child `/' the total number of times the child
was called. Recursive calls by the child are not
listed in the number after the `/'.
name This is the name of the child. The child's index
number is printed after it. If the child is a
member of a cycle, the cycle number is printed
between the name and the index number.
If there are any cycles (circles) in the call graph, there is an
entry for the cycle-as-a-whole. This entry shows who called the
cycle (as parents) and the members of the cycle (as children.)
The `+' recursive calls entry shows the number of function calls that
were internal to the cycle, and the calls entry for each member shows,
for that member, how many times it was called from other members of
the cycle.
Copyright (C) 2012-2014 Free Software Foundation, Inc.
Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.
Index by function name
[2] ai_best_move_rec [21] grid_apply_moves [3] grid_eval
[14] block_crust_get [7] grid_block_add [10] grid_init
[11] block_extreme [5] grid_block_center_top [9] grid_new
[13] block_get [8] grid_block_drop [24] grid_print
[25] block_init [18] grid_block_intersects [29] shape_new
[12] block_move [16] grid_block_remove [30] shape_stream_new
[17] block_new [15] grid_block_set_color [19] shape_stream_peek
[26] block_print [6] grid_block_valid [28] shape_stream_pop
[20] drop_amount [22] grid_clear_lines [4] shape_stream_test
[27] game_move_print [23] grid_cpy
Plus tard, je découvre que je les drapeaux -Ofast combinant et -pg, et la suppression de ces questions -Ofast arrange ci-dessus.
Mes questions sont les suivantes:
-ce que ces deux drapeaux incompatibles? Si je ne pouvais pas trouver un tel avertissement dans les docs
Si elles ne sont pas incompatibles, est-ce un bug de gcc?
Comment puis-je contourner ce problème pour voir les résultats de profilage correspondant aux optimisations les plus agressives afin de ne pas perdre de temps à optimiser le mauvais code?
Je pense que par «les choses que vous pouvez réparer», vous parlez d'optimisations de niveau supérieur. Mais dans ce cas, je suis intéressé à faire manuellement des optimisations de bas niveau. C'est pourquoi sans -je ne pense pas que je reçois une représentation précise des parties du code qui méritent mon attention. Je suis également très intéressé à comprendre pourquoi cette fonction non apparentée, non appelée, apparaît dans les statistiques, si les drapeaux sont incompatibles ou s'il s'agit d'un bug. – erjoalgo
@erjoalgo: Gosh, plusieurs points. Tout d'abord, même si gprof n'avait pas de bugs, [* il a beaucoup de problèmes *] (http://stackoverflow.com/a/1779343/23771), les gens pourraient se demander pourquoi vous prenez la peine de lutter avec lui. Deuxièmement, si la vitesse est votre objectif, pourquoi les optimisations de haut niveau ne valent-elles pas votre attention? Troisièmement, tout ce que vous pourriez faire pour accélérer le code de bas niveau est évident dans un code non optimisé. Si le compilateur optimise un peu de code de bas niveau, cela ne fait pas que les choses que vous * * * pourraient faire plus évidentes (même si * * * montraient toutes les fonctions). Si vous voulez, je vais essayer d'expliquer cela plus en détail. –
Sur ce projet particulier, j'ai investi suffisamment d'efforts dans la représentation des données et les algorithmes pour minimiser la complexité. J'ai donc déjà consacré beaucoup d'efforts à des optimisations de haut niveau, et j'aimerais attraper les fruits à portée de main. Par exemple, j'ai déjà gagné une accélération significative par le manuel en ligne de certains calculs, en s'éloignant d'une bibliothèque de tri, etc. – erjoalgo