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

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 <redacted>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Christophe Leroy <redacted>
Cc: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@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

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 [off-list ref] wrote:

On Thu, 22 Oct 2020 14:51:19 +0800, Pingfan Liu 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.

Applied to powerpc/next.

[1/1] powerpc/time: Enable sched clock for irqtime
      https://git.kernel.org/powerpc/c/b709e32ef570b8b91dfbcb63cffac4324c87799f

cheers