[PATCH] powerpc/time: enable sched clock for irqtime

[Pingfan Liu]

I encounter a irq flood on Power9 machine, and tries a way to work
around it by https://www.spinics.net/lists/kernel/msg3705028.html

As irq time accounting is the foundation for the method, it needs to
make irq accounting take effect on powerpc platform.

On Thu, Oct 22, 2020 at 2:51 PM Pingfan Liu <kernelfans at gmail.com> wrote:
>
> When CONFIG_IRQ_TIME_ACCOUNTING and CONFIG_VIRT_CPU_ACCOUNTING_GEN, powerpc
> does not enable "sched_clock_irqtime" and can not utilize irq time
> accounting.
>
> Like x86, powerpc does not use the sched_clock_register() interface. So it
> needs an dedicated call to enable_sched_clock_irqtime() to enable irq time
> accounting.
>
> Signed-off-by: Pingfan Liu <kernelfans at gmail.com>
> Cc: Michael Ellerman <mpe at ellerman.id.au>
> Cc: Christophe Leroy <christophe.leroy at c-s.fr>
> Cc: Nicholas Piggin <npiggin at gmail.com>
> To: linuxppc-dev at lists.ozlabs.org
> ---
>  arch/powerpc/kernel/time.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
> index f85539e..4083b59e 100644
> --- a/arch/powerpc/kernel/time.c
> +++ b/arch/powerpc/kernel/time.c
> @@ -53,6 +53,7 @@
>  #include <linux/of_clk.h>
>  #include <linux/suspend.h>
>  #include <linux/sched/cputime.h>
> +#include <linux/sched/clock.h>
>  #include <linux/processor.h>
>  #include <asm/trace.h>
>
> @@ -1134,6 +1135,7 @@ void __init time_init(void)
>         tick_setup_hrtimer_broadcast();
>
>         of_clk_init(NULL);
> +       enable_sched_clock_irqtime();
>  }
>
>  /*
> --
> 2.7.5
>