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authorIngo Molnar <mingo@elte.hu>2007-07-16 09:46:31 +0200
committerIngo Molnar <mingo@elte.hu>2007-07-16 09:46:31 +0200
commit5714d2de93fbb156c5e45fb101a2b4f0cae8fbb7 (patch)
tree50f6958246a6247e77816770989cb638c2ff99f1
parent[PATCH] sched: improve weight-array comments (diff)
downloadlinux-5714d2de93fbb156c5e45fb101a2b4f0cae8fbb7.tar.xz
linux-5714d2de93fbb156c5e45fb101a2b4f0cae8fbb7.zip
[PATCH] sched: document prio_to_wmult[]
document prio_to_wmult[]. Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/sched.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index a7284bc79cdf..90d22b72cf81 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -748,6 +748,13 @@ static const int prio_to_weight[40] = {
/* 10 */ 110, 87, 70, 56, 45, 36, 29, 23, 18, 15,
};
+/*
+ * Inverse (2^32/x) values of the prio_to_weight[] array, precalculated.
+ *
+ * In cases where the weight does not change often, we can use the
+ * precalculated inverse to speed up arithmetics by turning divisions
+ * into multiplications:
+ */
static const u32 prio_to_wmult[40] = {
48356, 60446, 75558, 94446, 118058, 147573,
184467, 230589, 288233, 360285, 450347,