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         printf("static const u32 runnable_avg_yN_inv[] = {");
  24         for (i = 0; i < HALFLIFE; i++) {
  25                 x = ((1UL<<32)-1)*pow(y, i);
  26
  27                 if (i % 6 == 0) printf("\n\t");
  28                 printf("0x%8x, ", x);
  29         }
  30         printf("\n};\n\n");
  31 }
  32
  33 int sum = 1024;
  34
  35 void calc_runnable_avg_yN_sum(void)
  36 {
  37         int i;
  38
  39         printf("static const u32 runnable_avg_yN_sum[] = {\n\t    0,");
  40         for (i = 1; i <= HALFLIFE; i++) {
  41                 if (i == 1)
  42                         sum *= y;
  43                 else
  44                         sum = sum*y + 1024*y;
  45
  46                 if (i % 11 == 0)
  47                         printf("\n\t");
  48
  49                 printf("%5d,", sum);
  50         }
  51         printf("\n};\n\n");
  52 }
  53
  54 int n = -1;
  55 /* first period */
  56 long max = 1024;
  57
  58 void calc_converged_max(void)
  59 {
  60         long last = 0, y_inv = ((1UL<<32)-1)*y;
  61
  62         for (; ; n++) {
  63                 if (n > -1)
  64                         max = ((max*y_inv)>>SHIFT) + 1024;
  65                         /*
  66                          * This is the same as:
  67                          * max = max*y + 1024;
  68                          */
  69
  70                 if (last == max)
  71                         break;
  72
  73                 last = max;
  74         }
  75         n--;
  76         printf("#define LOAD_AVG_PERIOD %d\n", HALFLIFE);
  77         printf("#define LOAD_AVG_MAX %ld\n", max);
  78 //      printf("#define LOAD_AVG_MAX_N %d\n\n", n);
  79 }
  80
  81 void calc_accumulated_sum_32(void)
  82 {
  83         int i, x = sum;
  84
  85         printf("static const u32 __accumulated_sum_N32[] = {\n\t     0,");
  86         for (i = 1; i <= n/HALFLIFE+1; i++) {
  87                 if (i > 1)
  88                         x = x/2 + sum;
  89
  90                 if (i % 6 == 0)
  91                         printf("\n\t");
  92
  93                 printf("%6d,", x);
  94         }
  95         printf("\n};\n\n");
  96 }
  97
  98 void main(void)
  99 {
 100         printf("/* Generated by Documentation/scheduler/sched-pelt; do not modify. */\n\n");
 101
 102         y = pow(0.5, 1/(double)HALFLIFE);
 103
 104         calc_runnable_avg_yN_inv();
 105 //      calc_runnable_avg_yN_sum();
 106         calc_converged_max();
 107 //      calc_accumulated_sum_32();
 108 }