Re: [PATCH] sched: generalize CONFIG_IRQ_TIME_ACCOUNTING for X86 and ARM

Cc'ing PeterZ.

On Wed, Feb 08, 2012 at 04:48:34AM -0800, Dmitry Antipov wrote:

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@google.com Signed-off-by: Dmitry Antipov dmitry.antipov@linaro.org

---

lib/Kconfig.debug | 12 ++++++++++++ lib/Makefile | 2 ++ lib/irqtime.c | 12 ++++++++++++

Do we need a single file for this? You know this feature is sched related, why not just move it to kernel/sched/core.c?

Thanks, Yong

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

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