GNU Linux-libre 4.19.211-gnu1
[releases.git] / Documentation / scheduler / sched-pelt.c
1 /*
2  * The following program is used to generate the constants for
3  * computing sched averages.
4  *
5  * ==============================================================
6  *              C program (compile with -lm)
7  * ==============================================================
8  */
9
10 #include <math.h>
11 #include <stdio.h>
12
13 #define HALFLIFE 32
14 #define SHIFT 32
15
16 double y;
17
18 void calc_runnable_avg_yN_inv(void)
19 {
20         int i;
21         unsigned int x;
22
23         /* To silence -Wunused-but-set-variable warnings. */
24         printf("static const u32 runnable_avg_yN_inv[] __maybe_unused = {");
25         for (i = 0; i < HALFLIFE; i++) {
26                 x = ((1UL<<32)-1)*pow(y, i);
27
28                 if (i % 6 == 0) printf("\n\t");
29                 printf("0x%8x, ", x);
30         }
31         printf("\n};\n\n");
32 }
33
34 int sum = 1024;
35
36 void calc_runnable_avg_yN_sum(void)
37 {
38         int i;
39
40         printf("static const u32 runnable_avg_yN_sum[] = {\n\t    0,");
41         for (i = 1; i <= HALFLIFE; i++) {
42                 if (i == 1)
43                         sum *= y;
44                 else
45                         sum = sum*y + 1024*y;
46
47                 if (i % 11 == 0)
48                         printf("\n\t");
49
50                 printf("%5d,", sum);
51         }
52         printf("\n};\n\n");
53 }
54
55 int n = -1;
56 /* first period */
57 long max = 1024;
58
59 void calc_converged_max(void)
60 {
61         long last = 0, y_inv = ((1UL<<32)-1)*y;
62
63         for (; ; n++) {
64                 if (n > -1)
65                         max = ((max*y_inv)>>SHIFT) + 1024;
66                         /*
67                          * This is the same as:
68                          * max = max*y + 1024;
69                          */
70
71                 if (last == max)
72                         break;
73
74                 last = max;
75         }
76         n--;
77         printf("#define LOAD_AVG_PERIOD %d\n", HALFLIFE);
78         printf("#define LOAD_AVG_MAX %ld\n", max);
79 //      printf("#define LOAD_AVG_MAX_N %d\n\n", n);
80 }
81
82 void calc_accumulated_sum_32(void)
83 {
84         int i, x = sum;
85
86         printf("static const u32 __accumulated_sum_N32[] = {\n\t     0,");
87         for (i = 1; i <= n/HALFLIFE+1; i++) {
88                 if (i > 1)
89                         x = x/2 + sum;
90
91                 if (i % 6 == 0)
92                         printf("\n\t");
93
94                 printf("%6d,", x);
95         }
96         printf("\n};\n\n");
97 }
98
99 void main(void)
100 {
101         printf("/* Generated by Documentation/scheduler/sched-pelt; do not modify. */\n\n");
102
103         y = pow(0.5, 1/(double)HALFLIFE);
104
105         calc_runnable_avg_yN_inv();
106 //      calc_runnable_avg_yN_sum();
107         calc_converged_max();
108 //      calc_accumulated_sum_32();
109 }