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authorYuyang Du <yuyang.du@intel.com>2017-02-12 22:44:22 +0100
committerIngo Molnar <mingo@kernel.org>2017-04-14 10:26:35 +0200
commit76d034edcf658e3c74fd90b149882ab1464e4af9 (patch)
treeadc0a9eb00d5deb9cf92a92c835cec358d4fd5a3 /Documentation
parentsched/fair: Fix corner case in __accumulate_sum() (diff)
downloadlinux-76d034edcf658e3c74fd90b149882ab1464e4af9.tar.xz
linux-76d034edcf658e3c74fd90b149882ab1464e4af9.zip
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@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: bsegall@google.com Cc: dietmar.eggemann@arm.com Cc: matt@codeblueprint.co.uk Cc: morten.rasmussen@arm.com Cc: pjt@google.com Cc: umgwanakikbuti@gmail.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1486935863-25251-2-git-send-email-yuyang.du@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/scheduler/sched-pelt.c108
1 files changed, 108 insertions, 0 deletions
diff --git a/Documentation/scheduler/sched-pelt.c b/Documentation/scheduler/sched-pelt.c
new file mode 100644
index 000000000000..e4219139386a
--- /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();
+}