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Message-ID: <CAJWu+oqXQ0N0gvKkPVBWJ3sA0rRLr7sg_N64gRTbtnLWjeEvRA@mail.gmail.com>
Date: Wed, 20 Sep 2017 11:51:38 -0700
From: Joel Fernandes <joelaf@...gle.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
Peter Zilstra <peterz@...radead.org>, kernel-team@...roid.com,
Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH v5 2/2] tracing: Add support for preempt and irq
enable/disable events
On Wed, Sep 20, 2017 at 11:23 AM, Steven Rostedt <rostedt@...dmis.org> wrote:
> On Tue, 12 Sep 2017 11:11:09 -0700
> Joel Fernandes <joelaf@...gle.com> wrote:
>
>> 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.
>>
>> Cc: Steven Rostedt <rostedt@...dmis.org>
>> Cc: Peter Zilstra <peterz@...radead.org>
>> Cc: kernel-team@...roid.com
>> Signed-off-by: Joel Fernandes <joelaf@...gle.com>
>> ---
>> include/linux/ftrace.h | 3 +-
>> include/linux/irqflags.h | 4 +--
>> include/trace/events/preemptirq.h | 62 +++++++++++++++++++++++++++++++++++++++
>> kernel/trace/Kconfig | 9 ++++++
>> kernel/trace/Makefile | 1 +
>> kernel/trace/trace_irqsoff.c | 57 ++++++++++++++++++++++++++++++++++-
>> 6 files changed, 132 insertions(+), 4 deletions(-)
>> create mode 100644 include/trace/events/preemptirq.h
>>
>> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
>> index 6383115e9d2c..5790ba7a85bd 100644
>> --- a/include/linux/ftrace.h
>> +++ b/include/linux/ftrace.h
>> @@ -742,7 +742,8 @@ 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
>> diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h
>> index 5dd1272d1ab2..6ad6732a4e98 100644
>> --- a/include/linux/irqflags.h
>> +++ b/include/linux/irqflags.h
>> @@ -44,8 +44,8 @@
>> # define INIT_TRACE_IRQFLAGS
>> #endif
>>
>> -#if defined(CONFIG_IRQSOFF_TRACER) || \
>> - defined(CONFIG_PREEMPT_TRACER)
>> +#if defined(CONFIG_IRQSOFF_TRACER) || defined(CONFIG_PREEMPT_TRACER) || \
>> + defined(CONFIG_PREEMPTIRQ_EVENTS)
>> extern void stop_critical_timings(void);
>> extern void start_critical_timings(void);
>> #else
>> diff --git a/include/trace/events/preemptirq.h b/include/trace/events/preemptirq.h
>> new file mode 100644
>> index 000000000000..601935e32cd1
>> --- /dev/null
>> +++ b/include/trace/events/preemptirq.h
>> @@ -0,0 +1,62 @@
>> +#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\n",
>
> No '\n', otherwise you add a lot of whitespace to the trace:
>
Sure will fix, thanks.
[..]
>> EXPORT_SYMBOL_GPL(stop_critical_timings);
>> @@ -792,24 +810,48 @@ EXPORT_SYMBOL_GPL(stop_critical_timings);
>> #if defined(CONFIG_TRACE_IRQFLAGS) && !defined(CONFIG_PROVE_LOCKING)
>> void trace_hardirqs_on(void)
>> {
>> + if (!this_cpu_read(tracing_irq_cpu))
>> + return;
>> +
>> + trace_irq_enable(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(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(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(CALLER_ADDR0, caller_addr);
>> tracer_hardirqs_off_caller(caller_addr);
>> }
>> EXPORT_SYMBOL(trace_hardirqs_off_caller);
>> @@ -831,14 +873,27 @@ 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)
>> {
>> + if (!this_cpu_read(tracing_preempt_cpu))
>> + return;
>> +
>> + trace_preempt_enable(a0, a1);
>> tracer_preempt_on(a0, a1);
>> +
>> + this_cpu_write(tracing_preempt_cpu, 0);
>> }
>>
>> void trace_preempt_off(unsigned long a0, unsigned long a1)
>> {
>> + if (this_cpu_read(tracing_preempt_cpu))
>> + return;
>> +
>> + this_cpu_write(tracing_preempt_cpu, 1);
>> +
>> + trace_preempt_disable(a0, a1);
>> tracer_preempt_off(a0, a1);
>> }
>> #endif
>
> Need to fold in the following patch as well. Otherwise RCU may have
> issues (run with lockdep enabled and you'll see all the splats).
Ok, will fix, thanks!
>
> -- Steve
>
> diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
> index 361a17f..7dcb431 100644
> --- a/kernel/trace/trace_irqsoff.c
> +++ b/kernel/trace/trace_irqsoff.c
> @@ -786,10 +786,10 @@ static DEFINE_PER_CPU(int, tracing_preempt_cpu);
> void start_critical_timings(void)
> {
> if (this_cpu_read(tracing_preempt_cpu))
> - trace_preempt_enable(CALLER_ADDR0, CALLER_ADDR1);
> + trace_preempt_enable_rcuidle(CALLER_ADDR0, CALLER_ADDR1);
>
> if (this_cpu_read(tracing_irq_cpu))
> - trace_irq_enable(CALLER_ADDR0, CALLER_ADDR1);
> + trace_irq_enable_rcuidle(CALLER_ADDR0, CALLER_ADDR1);
>
> start_critical_timings_tracer();
> }
> @@ -798,10 +798,10 @@ EXPORT_SYMBOL_GPL(start_critical_timings);
> void stop_critical_timings(void)
> {
> if (this_cpu_read(tracing_preempt_cpu))
> - trace_preempt_disable(CALLER_ADDR0, CALLER_ADDR1);
> + trace_preempt_disable_rcuidle(CALLER_ADDR0, CALLER_ADDR1);
>
> if (this_cpu_read(tracing_irq_cpu))
> - trace_irq_disable(CALLER_ADDR0, CALLER_ADDR1);
> + trace_irq_disable_rcuidle(CALLER_ADDR0, CALLER_ADDR1);
>
> stop_critical_timings_tracer();
> }
> @@ -813,7 +813,7 @@ void trace_hardirqs_on(void)
> if (!this_cpu_read(tracing_irq_cpu))
> return;
>
> - trace_irq_enable(CALLER_ADDR0, CALLER_ADDR1);
> + trace_irq_enable_rcuidle(CALLER_ADDR0, CALLER_ADDR1);
> tracer_hardirqs_on();
>
> this_cpu_write(tracing_irq_cpu, 0);
> @@ -827,7 +827,7 @@ void trace_hardirqs_off(void)
>
> this_cpu_write(tracing_irq_cpu, 1);
>
> - trace_irq_disable(CALLER_ADDR0, CALLER_ADDR1);
> + trace_irq_disable_rcuidle(CALLER_ADDR0, CALLER_ADDR1);
> tracer_hardirqs_off();
> }
> EXPORT_SYMBOL(trace_hardirqs_off);
> @@ -837,7 +837,7 @@ __visible void trace_hardirqs_on_caller(unsigned long caller_addr)
> if (!this_cpu_read(tracing_irq_cpu))
> return;
>
> - trace_irq_enable(CALLER_ADDR0, caller_addr);
> + trace_irq_enable_rcuidle(CALLER_ADDR0, caller_addr);
> tracer_hardirqs_on_caller(caller_addr);
>
> this_cpu_write(tracing_irq_cpu, 0);
> @@ -851,9 +851,9 @@ __visible void trace_hardirqs_off_caller(unsigned long caller_addr)
>
> this_cpu_write(tracing_irq_cpu, 1);
>
> - trace_irq_disable(CALLER_ADDR0, caller_addr);
> - tracer_hardirqs_off_caller(caller_addr);
> -}
> + trace_irq_disable_rcuidle(CALLER_ADDR0, caller_addr);
> + tracer_hardirqs_off_caller(caller_addr);}
> +
> EXPORT_SYMBOL(trace_hardirqs_off_caller);
>
> /*
> @@ -880,7 +880,7 @@ void trace_preempt_on(unsigned long a0, unsigned long a1)
> if (!this_cpu_read(tracing_preempt_cpu))
> return;
>
> - trace_preempt_enable(a0, a1);
> + trace_preempt_enable_rcuidle(a0, a1);
> tracer_preempt_on(a0, a1);
>
> this_cpu_write(tracing_preempt_cpu, 0);
> @@ -893,7 +893,7 @@ void trace_preempt_off(unsigned long a0, unsigned long a1)
>
> this_cpu_write(tracing_preempt_cpu, 1);
>
> - trace_preempt_disable(a0, a1);
> + trace_preempt_disable_rcuidle(a0, a1);
> tracer_preempt_off(a0, a1);
> }
> #endif
>
> --
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