Re: [Discuss] [PATCH] tracing, perf: add more power related events

[Thomas Renninger]

power-trace: Use power_switch_state instead of power_start and power_end

No need to have power_start and power_end. power_switch_state of state=0
means we exited power saving state. Userspace has all the information
it needs to detect power enter/exit case.

Export it, so that intel_idle can make use of it, even if compiled as module.

Signed-off-by: Thomas Renninger <tr...@suse.de>

---
 arch/x86/kernel/process.c   |    9 +++++++--
 drivers/cpuidle/cpuidle.c   |    3 +++
 drivers/idle/intel_idle.c   |    3 +++
 kernel/trace/power-traces.c |    2 +-
 4 files changed, 14 insertions(+), 3 deletions(-)

Index: linux-2.6.35-master/arch/x86/kernel/process.c
===================================================================
--- linux-2.6.35-master.orig/arch/x86/kernel/process.c
+++ linux-2.6.35-master/arch/x86/kernel/process.c
@@ -375,7 +375,10 @@ static inline int hlt_use_halt(void)
 void default_idle(void)
 {
        if (hlt_use_halt()) {
+               /* trace_power_start is deprecated, remove it after a while */
                trace_power_start(POWER_CSTATE, 1, smp_processor_id());
+               trace_power_switch_state(POWER_CSTATE, 1, smp_processor_id());
+
                current_thread_info()->status &= ~TS_POLLING;
                /*
                 * TS_POLLING-cleared state must be visible before we
@@ -446,6 +449,8 @@ EXPORT_SYMBOL_GPL(cpu_idle_wait);
 void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
 {
        trace_power_start(POWER_CSTATE, (ax>>4)+1, smp_processor_id());
+       trace_power_switch_state(POWER_CSTATE, (ax>>4)+1, smp_processor_id());
+
        if (!need_resched()) {
                if (cpu_has(&current_cpu_data, X86_FEATURE_CLFLUSH_MONITOR))
                        clflush((void *)&current_thread_info()->flags);
@@ -462,6 +467,8 @@ static void mwait_idle(void)
 {
        if (!need_resched()) {
                trace_power_start(POWER_CSTATE, 1, smp_processor_id());
+               trace_power_switch_state(POWER_CSTATE, 1, smp_processor_id());
+
                if (cpu_has(&current_cpu_data, X86_FEATURE_CLFLUSH_MONITOR))
                        clflush((void *)&current_thread_info()->flags);
 
@@ -482,11 +489,9 @@ static void mwait_idle(void)
  */
 static void poll_idle(void)
 {
-       trace_power_start(POWER_CSTATE, 0, smp_processor_id());
        local_irq_enable();
        while (!need_resched())
                cpu_relax();
-       trace_power_end(0);
 }
 
 /*
Index: linux-2.6.35-master/drivers/cpuidle/cpuidle.c
===================================================================
--- linux-2.6.35-master.orig/drivers/cpuidle/cpuidle.c
+++ linux-2.6.35-master/drivers/cpuidle/cpuidle.c
@@ -106,7 +106,10 @@ static void cpuidle_idle_call(void)
        /* give the governor an opportunity to reflect on the outcome */
        if (cpuidle_curr_governor->reflect)
                cpuidle_curr_governor->reflect(dev);
+
+       /* trace_power_end is deprecated, remove it after a while */
        trace_power_end(smp_processor_id());
+       trace_power_switch_state(POWER_CSTATE, 0, smp_processor_id());
 }
 
 /**
Index: linux-2.6.35-master/drivers/idle/intel_idle.c
===================================================================
--- linux-2.6.35-master.orig/drivers/idle/intel_idle.c
+++ linux-2.6.35-master/drivers/idle/intel_idle.c
@@ -192,8 +192,11 @@ static int intel_idle(struct cpuidle_dev
 
        stop_critical_timings();
 #ifndef MODULE
+       /* trace_power_start is deprecated, remove it after a while */
        trace_power_start(POWER_CSTATE, (eax >> 4) + 1, cpu);
 #endif
+       trace_power_switch_state(POWER_CSTATE, (eax >> 4) + 1, 
smp_processor_id());
+
        if (!need_resched()) {
 
                __monitor((void *)&current_thread_info()->flags, 0, 0);
Index: linux-2.6.35-master/kernel/trace/power-traces.c
===================================================================
--- linux-2.6.35-master.orig/kernel/trace/power-traces.c
+++ linux-2.6.35-master/kernel/trace/power-traces.c
@@ -13,4 +13,4 @@
 #define CREATE_TRACE_POINTS
 #include <trace/events/power.h>
 
-
+EXPORT_TRACEPOINT_SYMBOL_GPL(power_switch_state);
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