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tracing: Add support for preempt and irq enable/disable events

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Preempt and irq trace events can be used for tracing the start and
end of an atomic section which can be used by a trace viewer like
systrace to graphically view the start and end of an atomic section and
correlate them with latencies and scheduling issues.

This also serves as a prelude to using synthetic events or probes to
rewrite the preempt and irqsoff tracers, along with numerous benefits of
using trace events features for these events.
Link: http://lkml.kernel.org/r/20171006005432.14244-3-joelaf@google.com
Link: http://lkml.kernel.org/r/20171010225137.17370-1-joelaf@google.com

Cc: Peter Zilstra <peterz@infradead.org>
Cc: kernel-team@android.com
Signed-off-by: Joel Fernandes <joelaf@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Joel Fernandes
2017-10-10 15:51:37 -07:00
committed by Steven Rostedt (VMware)
parent aaecaa0b5f
commit d59158162e
5 changed files with 118 additions and 2 deletions
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35
kernel/trace/trace_irqsoff.c
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@@ -16,6 +16,9 @@
#include "trace.h"
#define CREATE_TRACE_POINTS
#include <trace/events/preemptirq.h>
#if defined(CONFIG_IRQSOFF_TRACER) || defined(CONFIG_PREEMPT_TRACER)
static struct trace_array *irqsoff_trace __read_mostly;
static int tracer_enabled __read_mostly;
@@ -777,26 +780,53 @@ static inline void tracer_preempt_off(unsigned long a0, unsigned long a1) { }
#endif
#if defined(CONFIG_TRACE_IRQFLAGS) && !defined(CONFIG_PROVE_LOCKING)
/* Per-cpu variable to prevent redundant calls when IRQs already off */
static DEFINE_PER_CPU(int, tracing_irq_cpu);
void trace_hardirqs_on(void)
{
if (!this_cpu_read(tracing_irq_cpu))
return;
trace_irq_enable_rcuidle(CALLER_ADDR0, CALLER_ADDR1);
tracer_hardirqs_on();
this_cpu_write(tracing_irq_cpu, 0);
}
EXPORT_SYMBOL(trace_hardirqs_on);
void trace_hardirqs_off(void)
{
if (this_cpu_read(tracing_irq_cpu))
return;
this_cpu_write(tracing_irq_cpu, 1);
trace_irq_disable_rcuidle(CALLER_ADDR0, CALLER_ADDR1);
tracer_hardirqs_off();
}
EXPORT_SYMBOL(trace_hardirqs_off);
__visible void trace_hardirqs_on_caller(unsigned long caller_addr)
{
if (!this_cpu_read(tracing_irq_cpu))
return;
trace_irq_enable_rcuidle(CALLER_ADDR0, caller_addr);
tracer_hardirqs_on_caller(caller_addr);
this_cpu_write(tracing_irq_cpu, 0);
}
EXPORT_SYMBOL(trace_hardirqs_on_caller);
__visible void trace_hardirqs_off_caller(unsigned long caller_addr)
{
if (this_cpu_read(tracing_irq_cpu))
return;
this_cpu_write(tracing_irq_cpu, 1);
trace_irq_disable_rcuidle(CALLER_ADDR0, caller_addr);
tracer_hardirqs_off_caller(caller_addr);
}
EXPORT_SYMBOL(trace_hardirqs_off_caller);
@@ -818,14 +848,17 @@ inline void print_irqtrace_events(struct task_struct *curr)
}
#endif
#ifdef CONFIG_PREEMPT_TRACER
#if defined(CONFIG_PREEMPT_TRACER) || \
(defined(CONFIG_DEBUG_PREEMPT) && defined(CONFIG_PREEMPTIRQ_EVENTS))
void trace_preempt_on(unsigned long a0, unsigned long a1)
{
trace_preempt_enable_rcuidle(a0, a1);
tracer_preempt_on(a0, a1);
}
void trace_preempt_off(unsigned long a0, unsigned long a1)
{
trace_preempt_disable_rcuidle(a0, a1);
tracer_preempt_off(a0, a1);
}
#endif