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Subject[Resend][PATCH V2] cpufreq: intel_pstate: allow trace in passive mode
Date
Allow use of the trace_pstate_sample trace function
when the intel_pstate driver is in passive mode.
Since the core_busy and scaled_busy fields are not
used, and it might be desirable to know which path
through the driver was used, either intel_cpufreq_target
or intel_cpufreq_fast_switch, re-task the core_busy
field as a flag indicator.

The user can then use the intel_pstate_tracer.py utility
to summarize and plot the trace.

In Passive mode the driver is only called if there is
a need to change the target frequency, so durations
(time gaps between calls) can be very very long. The user
needs to understand, and not be confused by, this limitation.

V2: prepare for resend. Rebase to current kernel, 4.15-rc3.
Signed-off-by: Doug Smythies <dsmythies@telus.net>
---
drivers/cpufreq/intel_pstate.c | 50 ++++++++++++++++++++++++++++++++++++++++--
1 file changed, 48 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 93a0e88..fe25d69 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -1949,7 +1949,10 @@ static int intel_cpufreq_target(struct cpufreq_policy *policy,
{
struct cpudata *cpu = all_cpu_data[policy->cpu];
struct cpufreq_freqs freqs;
- int target_pstate;
+ struct sample *sample;
+ int target_pstate, from;
+ u64 time;
+ bool sample_taken;

update_turbo_state();

@@ -1969,12 +1972,32 @@ static int intel_cpufreq_target(struct cpufreq_policy *policy,
break;
}
target_pstate = intel_pstate_prepare_request(cpu, target_pstate);
+
+ from = cpu->pstate.current_pstate;
+ time = ktime_get();
+ sample_taken = intel_pstate_sample(cpu, time);
+
if (target_pstate != cpu->pstate.current_pstate) {
cpu->pstate.current_pstate = target_pstate;
wrmsrl_on_cpu(policy->cpu, MSR_IA32_PERF_CTL,
pstate_funcs.get_val(cpu, target_pstate));
}
freqs.new = target_pstate * cpu->pstate.scaling;
+
+ if (sample_taken) {
+ intel_pstate_calc_avg_perf(cpu);
+ sample = &cpu->sample;
+ trace_pstate_sample(0,
+ 0,
+ from,
+ cpu->pstate.current_pstate,
+ sample->mperf,
+ sample->aperf,
+ sample->tsc,
+ get_avg_frequency(cpu),
+ fp_toint(cpu->iowait_boost * 100));
+ }
+
cpufreq_freq_transition_end(policy, &freqs, false);

return 0;
@@ -1984,13 +2007,36 @@ static unsigned int intel_cpufreq_fast_switch(struct cpufreq_policy *policy,
unsigned int target_freq)
{
struct cpudata *cpu = all_cpu_data[policy->cpu];
- int target_pstate;
+ struct sample *sample;
+ int target_pstate, from;
+ u64 time;
+ bool sample_taken;

update_turbo_state();

target_pstate = DIV_ROUND_UP(target_freq, cpu->pstate.scaling);
target_pstate = intel_pstate_prepare_request(cpu, target_pstate);
+
+ from = cpu->pstate.current_pstate;
+ time = ktime_get();
+ sample_taken = intel_pstate_sample(cpu, time);
+
intel_pstate_update_pstate(cpu, target_pstate);
+
+ if (sample_taken) {
+ intel_pstate_calc_avg_perf(cpu);
+ sample = &cpu->sample;
+ trace_pstate_sample(100,
+ 0,
+ from,
+ cpu->pstate.current_pstate,
+ sample->mperf,
+ sample->aperf,
+ sample->tsc,
+ get_avg_frequency(cpu),
+ fp_toint(cpu->iowait_boost * 100));
+ }
+
return target_pstate * cpu->pstate.scaling;
}

--
2.7.4
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