[tip:sched/core] sched/Documentation: Add 'sched-pelt' tool
From: tip-bot for Yuyang Du
Date: Fri Apr 14 2017 - 05:33:27 EST
Commit-ID: 76d034edcf658e3c74fd90b149882ab1464e4af9
Gitweb: http://git.kernel.org/tip/76d034edcf658e3c74fd90b149882ab1464e4af9
Author: Yuyang Du <yuyang.du@xxxxxxxxx>
AuthorDate: Mon, 13 Feb 2017 05:44:22 +0800
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 14 Apr 2017 10:26:35 +0200
sched/Documentation: Add 'sched-pelt' tool
Add a user-space program to compute/generate the PELT constants.
The kernel/sched/sched-pelt.h header will contain the output of
this program.
Signed-off-by: Yuyang Du <yuyang.du@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: bsegall@xxxxxxxxxx
Cc: dietmar.eggemann@xxxxxxx
Cc: matt@xxxxxxxxxxxxxxxxxxx
Cc: morten.rasmussen@xxxxxxx
Cc: pjt@xxxxxxxxxx
Cc: umgwanakikbuti@xxxxxxxxx
Cc: vincent.guittot@xxxxxxxxxx
Link: http://lkml.kernel.org/r/1486935863-25251-2-git-send-email-yuyang.du@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
Documentation/scheduler/sched-pelt.c | 108 +++++++++++++++++++++++++++++++++++
1 file changed, 108 insertions(+)
diff --git a/Documentation/scheduler/sched-pelt.c b/Documentation/scheduler/sched-pelt.c
new file mode 100644
index 0000000..e421913
--- /dev/null
+++ b/Documentation/scheduler/sched-pelt.c
@@ -0,0 +1,108 @@
+/*
+ * The following program is used to generate the constants for
+ * computing sched averages.
+ *
+ * ==============================================================
+ * C program (compile with -lm)
+ * ==============================================================
+ */
+
+#include <math.h>
+#include <stdio.h>
+
+#define HALFLIFE 32
+#define SHIFT 32
+
+double y;
+
+void calc_runnable_avg_yN_inv(void)
+{
+ int i;
+ unsigned int x;
+
+ printf("static const u32 runnable_avg_yN_inv[] = {");
+ for (i = 0; i < HALFLIFE; i++) {
+ x = ((1UL<<32)-1)*pow(y, i);
+
+ if (i % 6 == 0) printf("\n\t");
+ printf("0x%8x, ", x);
+ }
+ printf("\n};\n\n");
+}
+
+int sum = 1024;
+
+void calc_runnable_avg_yN_sum(void)
+{
+ int i;
+
+ printf("static const u32 runnable_avg_yN_sum[] = {\n\t 0,");
+ for (i = 1; i <= HALFLIFE; i++) {
+ if (i == 1)
+ sum *= y;
+ else
+ sum = sum*y + 1024*y;
+
+ if (i % 11 == 0)
+ printf("\n\t");
+
+ printf("%5d,", sum);
+ }
+ printf("\n};\n\n");
+}
+
+int n = -1;
+/* first period */
+long max = 1024;
+
+void calc_converged_max(void)
+{
+ long last = 0, y_inv = ((1UL<<32)-1)*y;
+
+ for (; ; n++) {
+ if (n > -1)
+ max = ((max*y_inv)>>SHIFT) + 1024;
+ /*
+ * This is the same as:
+ * max = max*y + 1024;
+ */
+
+ if (last == max)
+ break;
+
+ last = max;
+ }
+ n--;
+ printf("#define LOAD_AVG_PERIOD %d\n", HALFLIFE);
+ printf("#define LOAD_AVG_MAX %ld\n", max);
+// printf("#define LOAD_AVG_MAX_N %d\n\n", n);
+}
+
+void calc_accumulated_sum_32(void)
+{
+ int i, x = sum;
+
+ printf("static const u32 __accumulated_sum_N32[] = {\n\t 0,");
+ for (i = 1; i <= n/HALFLIFE+1; i++) {
+ if (i > 1)
+ x = x/2 + sum;
+
+ if (i % 6 == 0)
+ printf("\n\t");
+
+ printf("%6d,", x);
+ }
+ printf("\n};\n\n");
+}
+
+void main(void)
+{
+ printf("/* Generated by Documentation/scheduler/sched-pelt; do not modify. */\n\n");
+
+ y = pow(0.5, 1/(double)HALFLIFE);
+
+ calc_runnable_avg_yN_inv();
+// calc_runnable_avg_yN_sum();
+ calc_converged_max();
+// calc_accumulated_sum_32();
+}