ARM: Add irqtime accounting support
Add support for irq time accounting. This commit prepares ARM by adding
the call to enable_sched_clock_irqtime() in sched_clock(). We introduce
a new kernel parameter - irqtime - which takes an integer. -1 for auto,
0 for disabled, and 1 for enabled. Auto mode selects IRQ accounting if
we have a sched_clock() tick rate greater than 1MHz.
Frederic Weisbecker is working on a patch set which moves the
IRQ_TIME_ACCOUNTING into arch/, so that part is not incorporated into
this patch; this facility becomes available on ARM only when both this
patch and Frederic's patches are merged.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/sched_clock.c b/arch/arm/kernel/sched_clock.c
index 27d186a..9b8451a 100644
--- a/arch/arm/kernel/sched_clock.c
+++ b/arch/arm/kernel/sched_clock.c
@@ -9,6 +9,7 @@
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
+#include <linux/moduleparam.h>
#include <linux/sched.h>
#include <linux/syscore_ops.h>
#include <linux/timer.h>
@@ -25,6 +26,9 @@
static void sched_clock_poll(unsigned long wrap_ticks);
static DEFINE_TIMER(sched_clock_timer, sched_clock_poll, 0, 0);
+static int irqtime = -1;
+
+core_param(irqtime, irqtime, int, 0400);
static struct clock_data cd = {
.mult = NSEC_PER_SEC / HZ,
@@ -145,6 +149,10 @@
*/
cd.epoch_ns = 0;
+ /* Enable IRQ time accounting if we have a fast enough sched_clock */
+ if (irqtime > 0 || (irqtime == -1 && rate >= 1000000))
+ enable_sched_clock_irqtime();
+
pr_debug("Registered %pF as sched_clock source\n", read);
}