Commit d5915816 authored by Joel Fernandes's avatar Joel Fernandes Committed by Steven Rostedt (VMware)

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

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: default avatarJoel Fernandes <joelaf@google.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent aaecaa0b
......@@ -769,7 +769,8 @@ static inline unsigned long get_lock_parent_ip(void)
static inline void time_hardirqs_off(unsigned long a0, unsigned long a1) { }
#endif
#ifdef CONFIG_PREEMPT_TRACER
#if defined(CONFIG_PREEMPT_TRACER) || \
(defined(CONFIG_DEBUG_PREEMPT) && defined(CONFIG_PREEMPTIRQ_EVENTS))
extern void trace_preempt_on(unsigned long a0, unsigned long a1);
extern void trace_preempt_off(unsigned long a0, unsigned long a1);
#else
......
#ifdef CONFIG_PREEMPTIRQ_EVENTS
#undef TRACE_SYSTEM
#define TRACE_SYSTEM preemptirq
#if !defined(_TRACE_PREEMPTIRQ_H) || defined(TRACE_HEADER_MULTI_READ)
#define _TRACE_PREEMPTIRQ_H
#include <linux/ktime.h>
#include <linux/tracepoint.h>
#include <linux/string.h>
#include <asm/sections.h>
DECLARE_EVENT_CLASS(preemptirq_template,
TP_PROTO(unsigned long ip, unsigned long parent_ip),
TP_ARGS(ip, parent_ip),
TP_STRUCT__entry(
__field(u32, caller_offs)
__field(u32, parent_offs)
),
TP_fast_assign(
__entry->caller_offs = (u32)(ip - (unsigned long)_stext);
__entry->parent_offs = (u32)(parent_ip - (unsigned long)_stext);
),
TP_printk("caller=%pF parent=%pF",
(void *)((unsigned long)(_stext) + __entry->caller_offs),
(void *)((unsigned long)(_stext) + __entry->parent_offs))
);
#ifndef CONFIG_PROVE_LOCKING
DEFINE_EVENT(preemptirq_template, irq_disable,
TP_PROTO(unsigned long ip, unsigned long parent_ip),
TP_ARGS(ip, parent_ip));
DEFINE_EVENT(preemptirq_template, irq_enable,
TP_PROTO(unsigned long ip, unsigned long parent_ip),
TP_ARGS(ip, parent_ip));
#endif
#ifdef CONFIG_DEBUG_PREEMPT
DEFINE_EVENT(preemptirq_template, preempt_disable,
TP_PROTO(unsigned long ip, unsigned long parent_ip),
TP_ARGS(ip, parent_ip));
DEFINE_EVENT(preemptirq_template, preempt_enable,
TP_PROTO(unsigned long ip, unsigned long parent_ip),
TP_ARGS(ip, parent_ip));
#endif
#endif /* _TRACE_PREEMPTIRQ_H */
#include <trace/define_trace.h>
#else /* !CONFIG_PREEMPTIRQ_EVENTS */
#define trace_irq_enable(...)
#define trace_irq_disable(...)
#define trace_preempt_enable(...)
#define trace_preempt_disable(...)
#define trace_irq_enable_rcuidle(...)
#define trace_irq_disable_rcuidle(...)
#define trace_preempt_enable_rcuidle(...)
#define trace_preempt_disable_rcuidle(...)
#endif
......@@ -160,6 +160,17 @@ config FUNCTION_GRAPH_TRACER
address on the current task structure into a stack of calls.
config PREEMPTIRQ_EVENTS
bool "Enable trace events for preempt and irq disable/enable"
select TRACE_IRQFLAGS
depends on DEBUG_PREEMPT || !PROVE_LOCKING
default n
help
Enable tracing of disable and enable events for preemption and irqs.
For tracing preempt disable/enable events, DEBUG_PREEMPT must be
enabled. For tracing irq disable/enable events, PROVE_LOCKING must
be disabled.
config IRQSOFF_TRACER
bool "Interrupts-off Latency Tracer"
default n
......
......@@ -34,6 +34,7 @@ obj-$(CONFIG_TRACING) += trace_printk.o
obj-$(CONFIG_TRACING_MAP) += tracing_map.o
obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
obj-$(CONFIG_FUNCTION_TRACER) += trace_functions.o
obj-$(CONFIG_PREEMPTIRQ_EVENTS) += trace_irqsoff.o
obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o
obj-$(CONFIG_PREEMPT_TRACER) += trace_irqsoff.o
obj-$(CONFIG_SCHED_TRACER) += trace_sched_wakeup.o
......
......@@ -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
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment