Re: PATCH] ftrace: Add a C/P state tracer to help poweroptimization
From: Jason Baron
Date: Wed Feb 11 2009 - 13:58:47 EST
On Wed, Feb 11, 2009 at 10:30:29AM +0100, Ingo Molnar wrote:
> * Jason Baron <jbaron@xxxxxxxxxx> wrote:
>
> > On Mon, Oct 27, 2008 at 02:06:30PM -0700, Arjan van de Ven wrote:
> > > > Arjan van de Ven <arjan@xxxxxxxxxxxxx> writes:
> > > >
> > > > > [...]
> > > > > --- a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
> > > > > +++ b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
> > > > > [...]
> > > > > @@ -427,6 +429,8 @@ static int acpi_cpufreq_target(struct
> > > > > cpufreq_policy *policy, }
> > > > > }
> > > > >
> > > > > + trace_power_mark(&it, POWER_PSTATE, next_perf_state);
> > > > > +
> > > > > switch (data->cpu_feature) {
> > > > > case SYSTEM_INTEL_MSR_CAPABLE:
> > > > > cmd.type = SYSTEM_INTEL_MSR_CAPABLE;
> > > > > [...]
> > > >
> > > > Is there some reason that this doesn't use tracepoints instead
> > > > of such a single-backend hook?
> > >
> > > because it's a ton simpler this way? do simple things simpe and all
> > > that....
> > >
> >
> > hi,
> >
> > I wrote a patch to make c/p state tracer dependent on tracepoints and
> > then realized that the discussion had already been had. However, the
> > patch to use tracepoints is fairly simple, allows for other consumers,
> > and avoids a function call in the off case. please consider.
> >
> > thanks,
> >
> > -Jason
> >
> > Signed-off-by: Jason Baron <jbaron@xxxxxxxxxx>
> >
> > ---
> >
> > arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c | 3 +++
> > arch/x86/kernel/process.c | 4 ++++
> > include/linux/ftrace.h | 15 ---------------
> > include/trace/power.h | 18 ++++++++++++++++++
> > kernel/trace/trace_power.c | 28 ++++++++++++++++++++--------
> > 5 files changed, 45 insertions(+), 23 deletions(-)
> > create mode 100644 include/trace/power.h
>
> Looks good, but could you please base this on latest -tip? There's a number of
> pending changes in the tracing tree that conflict:
>
ok, re-based patch against latest -tip. Addresses Frédéric's
concerns as well.
thanks,
-Jason
Convert the c/p state "power" tracer to use tracepoints. Avoids a
function call when the tracer is disabled.
Signed-off-by: Jason Baron <jbaron@xxxxxxxxxx>
---
arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c | 2
arch/x86/kernel/process.c | 3
include/trace/power.h | 25 ++--
kernel/trace/trace_power.c | 173 +++++++++++++++++-----------
4 files changed, 119 insertions(+), 84 deletions(-)
diff --git a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
index 7ed925e..c5d737c 100644
--- a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
+++ b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
@@ -70,6 +70,8 @@ struct acpi_cpufreq_data {
static DEFINE_PER_CPU(struct acpi_cpufreq_data *, drv_data);
+DEFINE_TRACE(power_mark);
+
/* acpi_perf_data is a pointer to percpu data. */
static struct acpi_processor_performance *acpi_perf_data;
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 0f5d420..bf91350 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -19,6 +19,9 @@ EXPORT_SYMBOL(idle_nomwait);
struct kmem_cache *task_xstate_cachep;
+DEFINE_TRACE(power_start);
+DEFINE_TRACE(power_end);
+
int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
*dst = *src;
diff --git a/include/trace/power.h b/include/trace/power.h
index c7cefbc..2c733e5 100644
--- a/include/trace/power.h
+++ b/include/trace/power.h
@@ -2,6 +2,7 @@
#define _TRACE_POWER_H
#include <linux/ktime.h>
+#include <linux/tracepoint.h>
enum {
POWER_NONE = 0,
@@ -18,18 +19,16 @@ struct power_trace {
#endif
};
-#ifdef CONFIG_POWER_TRACER
-extern void trace_power_start(struct power_trace *it, unsigned int type,
- unsigned int state);
-extern void trace_power_mark(struct power_trace *it, unsigned int type,
- unsigned int state);
-extern void trace_power_end(struct power_trace *it);
-#else
-static inline void trace_power_start(struct power_trace *it, unsigned int type,
- unsigned int state) { }
-static inline void trace_power_mark(struct power_trace *it, unsigned int type,
- unsigned int state) { }
-static inline void trace_power_end(struct power_trace *it) { }
-#endif
+DECLARE_TRACE(power_start,
+ TPPROTO(struct power_trace *it, unsigned int type, unsigned int state),
+ TPARGS(it, type, state));
+
+DECLARE_TRACE(power_mark,
+ TPPROTO(struct power_trace *it, unsigned int type, unsigned int state),
+ TPARGS(it, type, state));
+
+DECLARE_TRACE(power_end,
+ TPPROTO(struct power_trace *it),
+ TPARGS(it));
#endif /* _TRACE_POWER_H */
diff --git a/kernel/trace/trace_power.c b/kernel/trace/trace_power.c
index b1d0d08..91ce672 100644
--- a/kernel/trace/trace_power.c
+++ b/kernel/trace/trace_power.c
@@ -21,15 +21,116 @@
static struct trace_array *power_trace;
static int __read_mostly trace_power_enabled;
+static void probe_power_start(struct power_trace *it, unsigned int type,
+ unsigned int level)
+{
+ if (!trace_power_enabled)
+ return;
+
+ memset(it, 0, sizeof(struct power_trace));
+ it->state = level;
+ it->type = type;
+ it->stamp = ktime_get();
+}
+
+
+static void probe_power_end(struct power_trace *it)
+{
+ struct ring_buffer_event *event;
+ struct trace_power *entry;
+ struct trace_array_cpu *data;
+ struct trace_array *tr = power_trace;
+
+ if (!trace_power_enabled)
+ return;
+
+ preempt_disable();
+ it->end = ktime_get();
+ data = tr->data[smp_processor_id()];
+
+ event = trace_buffer_lock_reserve(tr, TRACE_POWER,
+ sizeof(*entry), 0, 0);
+ if (!event)
+ goto out;
+ entry = ring_buffer_event_data(event);
+ entry->state_data = *it;
+ trace_buffer_unlock_commit(tr, event, 0, 0);
+ out:
+ preempt_enable();
+}
+
+static void probe_power_mark(struct power_trace *it, unsigned int type,
+ unsigned int level)
+{
+ struct ring_buffer_event *event;
+ struct trace_power *entry;
+ struct trace_array_cpu *data;
+ struct trace_array *tr = power_trace;
+
+ if (!trace_power_enabled)
+ return;
+
+ memset(it, 0, sizeof(struct power_trace));
+ it->state = level;
+ it->type = type;
+ it->stamp = ktime_get();
+ preempt_disable();
+ it->end = it->stamp;
+ data = tr->data[smp_processor_id()];
+
+ event = trace_buffer_lock_reserve(tr, TRACE_POWER,
+ sizeof(*entry), 0, 0);
+ if (!event)
+ goto out;
+ entry = ring_buffer_event_data(event);
+ entry->state_data = *it;
+ trace_buffer_unlock_commit(tr, event, 0, 0);
+ out:
+ preempt_enable();
+}
+
+static int tracing_power_register(void)
+{
+ int ret;
+
+ ret = register_trace_power_start(probe_power_start);
+ if (ret) {
+ pr_info("power trace: Couldn't activate tracepoint"
+ " probe to trace_power_start\n");
+ return ret;
+ }
+ ret = register_trace_power_end(probe_power_end);
+ if (ret) {
+ pr_info("power trace: Couldn't activate tracepoint"
+ " probe to trace_power_end\n");
+ goto fail_start;
+ }
+ ret = register_trace_power_mark(probe_power_mark);
+ if (ret) {
+ pr_info("power trace: Couldn't activate tracepoint"
+ " probe to trace_power_mark\n");
+ goto fail_end;
+ }
+ return ret;
+fail_end:
+ unregister_trace_power_end(probe_power_end);
+fail_start:
+ unregister_trace_power_start(probe_power_start);
+ return ret;
+}
static void start_power_trace(struct trace_array *tr)
{
trace_power_enabled = 1;
+ tracing_power_register();
}
static void stop_power_trace(struct trace_array *tr)
{
trace_power_enabled = 0;
+ unregister_trace_power_start(probe_power_start);
+ unregister_trace_power_end(probe_power_end);
+ unregister_trace_power_mark(probe_power_mark);
}
@@ -39,6 +140,7 @@ static int power_trace_init(struct trace_array *tr)
power_trace = tr;
trace_power_enabled = 1;
+ tracing_power_register();
for_each_cpu(cpu, cpu_possible_mask)
tracing_reset(tr, cpu);
@@ -95,74 +197,3 @@ static int init_power_trace(void)
return register_tracer(&power_tracer);
}
device_initcall(init_power_trace);
-
-void trace_power_start(struct power_trace *it, unsigned int type,
- unsigned int level)
-{
- if (!trace_power_enabled)
- return;
-
- memset(it, 0, sizeof(struct power_trace));
- it->state = level;
- it->type = type;
- it->stamp = ktime_get();
-}
-EXPORT_SYMBOL_GPL(trace_power_start);
-
-
-void trace_power_end(struct power_trace *it)
-{
- struct ring_buffer_event *event;
- struct trace_power *entry;
- struct trace_array_cpu *data;
- struct trace_array *tr = power_trace;
-
- if (!trace_power_enabled)
- return;
-
- preempt_disable();
- it->end = ktime_get();
- data = tr->data[smp_processor_id()];
-
- event = trace_buffer_lock_reserve(tr, TRACE_POWER,
- sizeof(*entry), 0, 0);
- if (!event)
- goto out;
- entry = ring_buffer_event_data(event);
- entry->state_data = *it;
- trace_buffer_unlock_commit(tr, event, 0, 0);
- out:
- preempt_enable();
-}
-EXPORT_SYMBOL_GPL(trace_power_end);
-
-void trace_power_mark(struct power_trace *it, unsigned int type,
- unsigned int level)
-{
- struct ring_buffer_event *event;
- struct trace_power *entry;
- struct trace_array_cpu *data;
- struct trace_array *tr = power_trace;
-
- if (!trace_power_enabled)
- return;
-
- memset(it, 0, sizeof(struct power_trace));
- it->state = level;
- it->type = type;
- it->stamp = ktime_get();
- preempt_disable();
- it->end = it->stamp;
- data = tr->data[smp_processor_id()];
-
- event = trace_buffer_lock_reserve(tr, TRACE_POWER,
- sizeof(*entry), 0, 0);
- if (!event)
- goto out;
- entry = ring_buffer_event_data(event);
- entry->state_data = *it;
- trace_buffer_unlock_commit(tr, event, 0, 0);
- out:
- preempt_enable();
-}
-EXPORT_SYMBOL_GPL(trace_power_mark);
--
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