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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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