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ARM: Add irqtime accounting support

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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>
This commit is contained in:
Russell King 2012-09-09 18:39:28 +01:00
parent a67e1ce145
commit a42c362980
1 changed files with 8 additions and 0 deletions
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8
arch/arm/kernel/sched_clock.c
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@ -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 @@ struct clock_data {
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 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
*/
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);
}