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

[Venki Pallipadi]

On Tue, Feb 7, 2012 at 10:06 AM, Dmitry Antipov
<dmitry.antipov@xxxxxxxxxx> wrote:
> Generalize CONFIG_IRQ_TIME_ACCOUNTING  between X86 and
> ARM, move "noirqtime=" option to common debugging code.
>
> Signed-off-by: Dmitry Antipov <dmitry.antipov@xxxxxxxxxx>
> ---
>  arch/arm/kernel/sched_clock.c |    3 +++
>  arch/x86/Kconfig              |   11 -----------
>  arch/x86/kernel/tsc.c         |    4 ----
>  include/linux/sched.h         |    2 ++
>  lib/Kconfig.debug             |   12 ++++++++++++
>  lib/Makefile                  |    2 ++
>  lib/irqtime.c                 |   12 ++++++++++++
>  7 files changed, 31 insertions(+), 15 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..a3a5465 100644
> --- a/arch/x86/kernel/tsc.c
> +++ b/arch/x86/kernel/tsc.c
> @@ -103,14 +103,10 @@ 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))
> -               no_sched_irq_time = 1;

I guess we need to keep this option around and gracefully deprecate to
the new one?

>        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..a55287e 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 DEBUG_KERNEL && (X86 || (ARM && HAVE_SCHED_CLOCK))

Why the new dependency on DEBUG_KERNEL?

Thanks,
-Venki

> +       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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