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Subject[RFC PATCH v4 6/6] sched/cpufreq: Add schedutil_em_tp tracepoint
Date
Introduce a new tracepoint reporting the effect of using the Energy
Model inside get_next_freq() in schedutil.

Signed-off-by: Douglas RAILLARD <douglas.raillard@arm.com>
---
include/trace/events/power.h | 9 +++++++++
kernel/sched/cpufreq_schedutil.c | 20 ++++++++++++++------
2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/include/trace/events/power.h b/include/trace/events/power.h
index 7457e238e1b7..a3df4e915f5b 100644
--- a/include/trace/events/power.h
+++ b/include/trace/events/power.h
@@ -525,6 +525,15 @@ DEFINE_EVENT(dev_pm_qos_request, dev_pm_qos_remove_request,

TP_ARGS(name, type, new_value)
);
+
+DECLARE_TRACE(schedutil_em_tp,
+ TP_PROTO(unsigned int cpu, unsigned long util,
+ unsigned int cost_margin, unsigned int policy_cost_margin,
+ unsigned int base_freq, unsigned int boosted_freq),
+ TP_ARGS(cpu, util, cost_margin, policy_cost_margin, base_freq,
+ boosted_freq)
+);
+
#endif /* _TRACE_POWER_H */

/* This part must be outside protection */
diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 9a7617ea7bf4..8909c752c06f 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -14,6 +14,8 @@
#include <linux/sched/cpufreq.h>
#include <trace/events/power.h>

+EXPORT_TRACEPOINT_SYMBOL_GPL(schedutil_em_tp);
+
#define IOWAIT_BOOST_MIN (SCHED_CAPACITY_SCALE / 8)

struct sugov_tunables {
@@ -225,7 +227,7 @@ static unsigned long sugov_cpu_ramp_boost_update(struct sugov_cpu *sg_cpu)

/**
* get_next_freq - Compute a new frequency for a given cpufreq policy.
- * @sg_policy: schedutil policy object to compute the new frequency for.
+ * @sg_cpu: schedutil CPU object to compute the new frequency for.
* @util: Current CPU utilization.
* @max: CPU capacity.
* @boost: Extra power that can be spent on top of the minimum amount of power
@@ -248,22 +250,28 @@ static unsigned long sugov_cpu_ramp_boost_update(struct sugov_cpu *sg_cpu)
* next_freq (as calculated above) is returned, subject to policy min/max and
* cpufreq driver limitations.
*/
-static unsigned int get_next_freq(struct sugov_policy *sg_policy,
+static unsigned int get_next_freq(struct sugov_cpu *sg_cpu,
unsigned long util, unsigned long max,
unsigned long boost)
{
+ struct sugov_policy *sg_policy = sg_cpu->sg_policy;
struct cpufreq_policy *policy = sg_policy->policy;
unsigned int freq = arch_scale_freq_invariant() ?
policy->cpuinfo.max_freq : policy->cur;
struct em_perf_domain *pd = sugov_policy_get_pd(sg_policy);
+ unsigned int base_freq;

- freq = map_util_freq(util, freq, max);
+ base_freq = map_util_freq(util, freq, max);

/*
* Try to get a higher frequency if one is available, given the extra
* power we are ready to spend.
*/
- freq = em_pd_get_higher_freq(pd, freq, boost);
+ freq = em_pd_get_higher_freq(pd, base_freq, boost);
+
+ trace_schedutil_em_tp(sg_cpu->cpu, util,
+ sugov_cpu_ramp_boost(sg_cpu), boost,
+ base_freq, freq);

if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
return sg_policy->next_freq;
@@ -562,7 +570,7 @@ static void sugov_update_single(struct update_util_data *hook, u64 time,
ramp_boost = sugov_cpu_ramp_boost_update(sg_cpu);
max = sg_cpu->max;
util = sugov_iowait_apply(sg_cpu, time, util, max);
- next_f = get_next_freq(sg_policy, util, max, ramp_boost);
+ next_f = get_next_freq(sg_cpu, util, max, ramp_boost);
/*
* Do not reduce the frequency if the CPU has not been idle
* recently, as the reduction is likely to be premature then.
@@ -616,7 +624,7 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
}
}

- return get_next_freq(sg_policy, util, max, ramp_boost);
+ return get_next_freq(sg_cpu, util, max, ramp_boost);
}

static void
--
2.24.1
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