[PATCH 23/24] jrcu: better timer slop

From: Joe Korty
Date: Thu Mar 24 2011 - 13:50:17 EST


jrcu: fix broken timer slop

The expression

USEC_PER_SEC / (HZ * 3 / 2)

was trying to define a period, in usec, some 50% larger
than the natural HZ period. Instead it made a period
some 30% shorter.

But such attempts are completely unnecessary. HZ alone
works just fine.

Signed-off-by: Joe Korty <joe.korty@xxxxxxxx>

Index: b/kernel/jrcu.c
===================================================================
--- a/kernel/jrcu.c
+++ b/kernel/jrcu.c
@@ -131,7 +131,7 @@ static struct rcu_stats {

#define RCU_HZ (20)
#define RCU_HZ_PERIOD_US (USEC_PER_SEC / RCU_HZ)
-#define RCU_HZ_DELTA_US (USEC_PER_SEC / (HZ * 3 / 2))
+#define RCU_HZ_DELTA_US (USEC_PER_SEC / HZ)

static int rcu_hz = RCU_HZ;
static int rcu_hz_period_us = RCU_HZ_PERIOD_US;
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