[PATCH] sched: generalize CONFIG_IRQ_TIME_ACCOUNTING for X86 and ARM

[Dmitry Antipov]

Generalize CONFIG_IRQ_TIME_ACCOUNTING  between X86 and
ARM, move "noirqtime=" option to common debugging code.
For a bit of backward compatibility, "tsc=noirqtime"
is preserved, but issues a warning.

Suggested-by: Venki Pallipadi <venki at google.com>
Signed-off-by: Dmitry Antipov <dmitry.antipov at linaro.org>
---
 arch/arm/kernel/sched_clock.c |    3 +++
 arch/x86/Kconfig              |   11 -----------
 arch/x86/kernel/tsc.c         |    7 ++++---
 include/linux/sched.h         |    2 ++
 lib/Kconfig.debug             |   12 ++++++++++++
 lib/Makefile                  |    2 ++
 lib/irqtime.c                 |   12 ++++++++++++
 7 files changed, 35 insertions(+), 14 deletions(-)
 create mode 100644 lib/irqtime.c

diff --git a/arch/arm/kernel/sched_clock.c b/arch/arm/kernel/sched_clock.c
index 5416c7c..56d2a9d 100644
--- a/arch/arm/kernel/sched_clock.c
+++ b/arch/arm/kernel/sched_clock.c
@@ -162,5 +162,8 @@ void __init sched_clock_postinit(void)
 	if (read_sched_clock == jiffy_sched_clock_read)
 		setup_sched_clock(jiffy_sched_clock_read, 32, HZ);
 
+	if (!no_sched_irq_time)
+		enable_sched_clock_irqtime();
+
 	sched_clock_poll(sched_clock_timer.data);
 }
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 5bed94e..4759676 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -805,17 +805,6 @@ config SCHED_MC
 	  making when dealing with multi-core CPU chips at a cost of slightly
 	  increased overhead in some places. If unsure say N here.
 
-config IRQ_TIME_ACCOUNTING
-	bool "Fine granularity task level IRQ time accounting"
-	default n
-	---help---
-	  Select this option to enable fine granularity task irq time
-	  accounting. This is done by reading a timestamp on each
-	  transitions between softirq and hardirq state, so there can be a
-	  small performance impact.
-
-	  If in doubt, say N here.
-
 source "kernel/Kconfig.preempt"
 
 config X86_UP_APIC
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index a62c201..70510a3 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -103,14 +103,15 @@ int __init notsc_setup(char *str)
 
 __setup("notsc", notsc_setup);
 
-static int no_sched_irq_time;
-
 static int __init tsc_setup(char *str)
 {
 	if (!strcmp(str, "reliable"))
 		tsc_clocksource_reliable = 1;
-	if (!strncmp(str, "noirqtime", 9))
+	if (!strncmp(str, "noirqtime", 9)) {
+		printk(KERN_WARNING "tsc: tsc=noirqtime is "
+		       "obsolete, use noirqtime instead\n");
 		no_sched_irq_time = 1;
+	}
 	return 1;
 }
 
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 7d379a6..b3575b5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1966,9 +1966,11 @@ extern void sched_clock_idle_wakeup_event(u64 delta_ns);
  * The reason for this explicit opt-in is not to have perf penalty with
  * slow sched_clocks.
  */
+extern int no_sched_irq_time;
 extern void enable_sched_clock_irqtime(void);
 extern void disable_sched_clock_irqtime(void);
 #else
+#define no_sched_irq_time 1
 static inline void enable_sched_clock_irqtime(void) {}
 static inline void disable_sched_clock_irqtime(void) {}
 #endif
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 8745ac7..48be210 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -299,6 +299,18 @@ config SCHEDSTATS
 	  application, you can say N to avoid the very slight overhead
 	  this adds.
 
+config IRQ_TIME_ACCOUNTING
+	bool "Fine granularity task level IRQ time accounting"
+	depends on (X86 || (ARM && HAVE_SCHED_CLOCK))
+	default n
+	---help---
+	  Select this option to enable fine granularity task irq time
+	  accounting. This is done by reading a timestamp on each
+	  transitions between softirq and hardirq state, so there can be a
+	  small performance impact.
+
+	  If in doubt, say N here.
+
 config TIMER_STATS
 	bool "Collect kernel timers statistics"
 	depends on DEBUG_KERNEL && PROC_FS
diff --git a/lib/Makefile b/lib/Makefile
index 18515f0..44d67d4 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -49,6 +49,8 @@ obj-$(CONFIG_DEBUG_PREEMPT) += smp_processor_id.o
 obj-$(CONFIG_DEBUG_LIST) += list_debug.o
 obj-$(CONFIG_DEBUG_OBJECTS) += debugobjects.o
 
+obj-$(CONFIG_IRQ_TIME_ACCOUNTING) += irqtime.o
+
 ifneq ($(CONFIG_HAVE_DEC_LOCK),y)
   lib-y += dec_and_lock.o
 endif
diff --git a/lib/irqtime.c b/lib/irqtime.c
new file mode 100644
index 0000000..10d440d
--- /dev/null
+++ b/lib/irqtime.c
@@ -0,0 +1,12 @@
+#include <linux/kernel.h>
+#include <linux/sched.h>
+
+int no_sched_irq_time;
+
+static int __init irqtime_setup(char *str)
+{
+	no_sched_irq_time = 1;
+	return 1;
+}
+
+__setup("noirqtime", irqtime_setup);
-- 
1.7.7.6