[PATCH] sched: generalize CONFIG_IRQ_TIME_ACCOUNTING for X86 and ARM
Dmitry Antipov
dmitry.antipov at linaro.org
Wed Feb 8 18:58:36 EST 2012
Generalize CONFIG_IRQ_TIME_ACCOUNTING between X86 and
ARM, move "noirqtime=" option to common debugging code.
For a bit of backward compatibility, X86-specific option
"tsc=noirqtime" is preserved, but issues a warning.
Suggested-by: Russell King <rmk+kernel at arm.linux.org.uk>
Suggested-by: Venki Pallipadi <venki at google.com>
Signed-off-by: Dmitry Antipov <dmitry.antipov at linaro.org>
---
Documentation/kernel-parameters.txt | 9 +++++----
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 ++++++++++++
8 files changed, 40 insertions(+), 18 deletions(-)
create mode 100644 lib/irqtime.c
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 033d4e6..b64a13f 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1719,6 +1719,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
noautogroup Disable scheduler automatic task group creation.
+ noirqtime [X86,ARM] Used to run time disable IRQ_TIME_ACCOUNTING,
+ should give a negligible performance improvement.
+
nobats [PPC] Do not use BATs for mapping kernel lowmem
on "Classic" PPC cores.
@@ -2636,10 +2639,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
as the stability checks done at bootup. Used to enable
high-resolution timer mode on older hardware, and in
virtualized environment.
- [x86] noirqtime: Do not use TSC to do irq accounting.
- Used to run time disable IRQ_TIME_ACCOUNTING on any
- platforms where RDTSC is slow and this accounting
- can add overhead.
+ [x86] noirqtime: obsoleted by "noirqtime" generic option,
+ see it's documentation for details.
turbografx.map[2|3]= [HW,JOY]
TurboGraFX parallel port interface
diff --git a/arch/arm/kernel/sched_clock.c b/arch/arm/kernel/sched_clock.c
index 5416c7c..961bd2d 100644
--- a/arch/arm/kernel/sched_clock.c
+++ b/arch/arm/kernel/sched_clock.c
@@ -144,6 +144,9 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
*/
cd.epoch_ns = 0;
+ if (!no_sched_irq_time)
+ enable_sched_clock_irqtime();
+
pr_debug("Registered %pF as sched_clock source\n", read);
}
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..236e814 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
+ 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
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