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    SubjectRe: [PATCH 05/17] trace: energy_model: Add trace event for EM runtime modifications
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    Hello Lukasz,
    Just a suggestion, maybe it would be good to trace the CPUs affected by
    the modification. It is possible to retrieve this information by going
    to /sys/kernel/debug/energy_model/xxx/cpus, but might be simpler when
    parsing a trace.

    Regards,
    Pierre

    On 3/14/23 11:33, Lukasz Luba wrote:
    > The Energy Model (EM) supports runtime modifications. Track the changes
    > in order to do post-processing analysis. Don't use arrays in the trace
    > event, since they are not properly supported by the tools. Instead use
    > simple "unroll" with emitting the trace event for each EM array entry
    > with proper ID information. The older debugging mechanism which was
    > the simple debugfs which dumping the EM content won't be sufficient for
    > the modifiable EM purpose. This trace event mechanism would address the
    > needs.
    >
    > Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
    > ---
    > include/trace/events/energy_model.h | 46 +++++++++++++++++++++++++++++
    > kernel/power/energy_model.c | 3 ++
    > 2 files changed, 49 insertions(+)
    > create mode 100644 include/trace/events/energy_model.h
    >
    > diff --git a/include/trace/events/energy_model.h b/include/trace/events/energy_model.h
    > new file mode 100644
    > index 000000000000..f70babeb5dde
    > --- /dev/null
    > +++ b/include/trace/events/energy_model.h
    > @@ -0,0 +1,46 @@
    > +/* SPDX-License-Identifier: GPL-2.0 */
    > +#undef TRACE_SYSTEM
    > +#define TRACE_SYSTEM energy_model
    > +
    > +#if !defined(_TRACE_ENERGY_MODEL_H) || defined(TRACE_HEADER_MULTI_READ)
    > +#define _TRACE_ENERGY_MODEL_H
    > +
    > +#include <linux/tracepoint.h>
    > +
    > +TRACE_EVENT(em_perf_state,
    > + TP_PROTO(const char *dev_name, int nr_perf_states, int state,
    > + unsigned long ps_frequency, unsigned long ps_power,
    > + unsigned long ps_cost, unsigned long ps_flags),
    > +
    > + TP_ARGS(dev_name, nr_perf_states, state, ps_frequency, ps_power, ps_cost,
    > + ps_flags),
    > +
    > + TP_STRUCT__entry(
    > + __string(name, dev_name)
    > + __field(int, num_states)
    > + __field(int, state)
    > + __field(unsigned long, frequency)
    > + __field(unsigned long, power)
    > + __field(unsigned long, cost)
    > + __field(unsigned long, flags)
    > + ),
    > +
    > + TP_fast_assign(
    > + __assign_str(name, dev_name);
    > + __entry->num_states = nr_perf_states;
    > + __entry->state = state;
    > + __entry->frequency = ps_frequency;
    > + __entry->power = ps_power;
    > + __entry->cost = ps_cost;
    > + __entry->flags = ps_flags;
    > + ),
    > +
    > + TP_printk("dev_name=%s nr_perf_states=%d state=%d frequency=%lu power=%lu cost=%lu flags=%lu",
    > + __get_str(name), __entry->num_states, __entry->state,
    > + __entry->frequency, __entry->power, __entry->cost,
    > + __entry->flags)
    > +);
    > +#endif /* _TRACE_ENERGY_MODEL_H */
    > +
    > +/* This part must be outside protection */
    > +#include <trace/define_trace.h>
    > diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
    > index 937e98a71ed5..3b778743ba89 100644
    > --- a/kernel/power/energy_model.c
    > +++ b/kernel/power/energy_model.c
    > @@ -17,6 +17,9 @@
    > #include <linux/sched/topology.h>
    > #include <linux/slab.h>
    >
    > +#define CREATE_TRACE_POINTS
    > +#include <trace/events/energy_model.h>
    > +
    > /*
    > * Mutex serializing the registrations of performance domains and letting
    > * callbacks defined by drivers sleep.

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