[PATCH] arm64: don't account for cpu offline time with irqsoff tracer

Zhizhou Zhang zhizhouzhang at asrmicro.com
Wed Sep 5 01:19:43 PDT 2018


This is no need to account for cpu offline time with irqsoff tracer.
We can trigger a large irqsoff latency with below commands:

$ echo irqsoff > /sys/kernel/debug/tracing/current_tracer
$ echo 0 > /sys/kernel/debug/tracing/options/function-trace
$ echo 1 > /sys/kernel/debug/tracing/tracing_on
$ echo 0 > /sys/devices/system/cpu/cpu1/online
$ # wait a while ...
$ echo 1 > /sys/devices/system/cpu/cpu1/online
$ cat /sys/kernel/debug/tracing/trace

Signed-off-by: Zhizhou Zhang <zhizhouzhang at asrmicro.com>
---
 arch/arm64/kernel/smp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 25fcd22..faed8f6 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -346,6 +346,7 @@ void cpu_die(void)
 	idle_task_exit();
 
 	local_daif_mask();
+	stop_critical_timings();
 
 	/* Tell __cpu_die() that this CPU is now safe to dispose of */
 	(void)cpu_report_death();
-- 
1.9.1




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