Documentation/scheduler/sched-pelt.c

0001 /*
0002  * The following program is used to generate the constants for
0003  * computing sched averages.
0004  *
0005  * ==============================================================
0006  *      C program (compile with -lm)
0007  * ==============================================================
0008  */
0009
0010 #include <math.h>
0011 #include <stdio.h>
0012
0013 #define HALFLIFE 32
0014 #define SHIFT 32
0015
0016 double y;
0017
0018 void calc_runnable_avg_yN_inv(void)
0019 {
0020     int i;
0021     unsigned int x;
0022
0023     /* To silence -Wunused-but-set-variable warnings. */
0024     printf("static const u32 runnable_avg_yN_inv[] __maybe_unused = {");
0025     for (i = 0; i < HALFLIFE; i++) {
0026         x = ((1UL<<32)-1)*pow(y, i);
0027
0028         if (i % 6 == 0) printf("\n\t");
0029         printf("0x%8x, ", x);
0030     }
0031     printf("\n};\n\n");
0032 }
0033
0034 int sum = 1024;
0035
0036 void calc_runnable_avg_yN_sum(void)
0037 {
0038     int i;
0039
0040     printf("static const u32 runnable_avg_yN_sum[] = {\n\t    0,");
0041     for (i = 1; i <= HALFLIFE; i++) {
0042         if (i == 1)
0043             sum *= y;
0044         else
0045             sum = sum*y + 1024*y;
0046
0047         if (i % 11 == 0)
0048             printf("\n\t");
0049
0050         printf("%5d,", sum);
0051     }
0052     printf("\n};\n\n");
0053 }
0054
0055 int n = -1;
0056 /* first period */
0057 long max = 1024;
0058
0059 void calc_converged_max(void)
0060 {
0061     long last = 0, y_inv = ((1UL<<32)-1)*y;
0062
0063     for (; ; n++) {
0064         if (n > -1)
0065             max = ((max*y_inv)>>SHIFT) + 1024;
0066             /*
0067              * This is the same as:
0068              * max = max*y + 1024;
0069              */
0070
0071         if (last == max)
0072             break;
0073
0074         last = max;
0075     }
0076     n--;
0077     printf("#define LOAD_AVG_PERIOD %d\n", HALFLIFE);
0078     printf("#define LOAD_AVG_MAX %ld\n", max);
0079 //  printf("#define LOAD_AVG_MAX_N %d\n\n", n);
0080 }
0081
0082 void calc_accumulated_sum_32(void)
0083 {
0084     int i, x = sum;
0085
0086     printf("static const u32 __accumulated_sum_N32[] = {\n\t     0,");
0087     for (i = 1; i <= n/HALFLIFE+1; i++) {
0088         if (i > 1)
0089             x = x/2 + sum;
0090
0091         if (i % 6 == 0)
0092             printf("\n\t");
0093
0094         printf("%6d,", x);
0095     }
0096     printf("\n};\n\n");
0097 }
0098
0099 void main(void)
0100 {
0101     printf("/* Generated by Documentation/scheduler/sched-pelt; do not modify. */\n\n");
0102
0103     y = pow(0.5, 1/(double)HALFLIFE);
0104
0105     calc_runnable_avg_yN_inv();
0106 //  calc_runnable_avg_yN_sum();
0107     calc_converged_max();
0108 //  calc_accumulated_sum_32();
0109 }