From: Douglas RAILLARD <douglas.raillard@arm.com>
To: linux-kernel@vger.kernel.org
Cc: linux-pm@vger.kernel.org, mingo@redhat.com, peterz@infradead.org,
rjw@rjwysocki.net, viresh.kumar@linaro.org,
quentin.perret@arm.com, douglas.raillard@arm.com,
patrick.bellasi@arm.com, dietmar.eggemann@arm.com
Subject: [RFC PATCH v2 1/5] PM: Introduce em_pd_get_higher_freq()
Date: Thu, 27 Jun 2019 18:15:59 +0100 [thread overview]
Message-ID: <20190627171603.14767-2-douglas.raillard@arm.com> (raw)
In-Reply-To: <20190627171603.14767-1-douglas.raillard@arm.com>
em_pd_get_higher_freq() returns a frequency greater or equal to the
provided one while taking into account a given cost margin. It also
skips inefficient OPPs that have a higher cost than another one with a
higher frequency.
The efficiency of an OPP is measured as efficiency=capacity/power.
OPPs with the same efficiency are assumed to be equivalent, since they
will consume as much energy for a given amount of work to do. That may
take more or less time depending on the frequency, but will consume the
same energy.
Signed-off-by: Douglas RAILLARD <douglas.raillard@arm.com>
---
include/linux/energy_model.h | 53 ++++++++++++++++++++++++++++++++++++
1 file changed, 53 insertions(+)
diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
index aa027f7bcb3e..cc9819967f8d 100644
--- a/include/linux/energy_model.h
+++ b/include/linux/energy_model.h
@@ -159,6 +159,53 @@ static inline int em_pd_nr_cap_states(struct em_perf_domain *pd)
return pd->nr_cap_states;
}
+#define EM_COST_MARGIN_SCALE 1024U
+
+/**
+ * em_pd_get_higher_freq() - Get the highest frequency that does not exceed the
+ * given cost margin compared to min_freq
+ * @pd : performance domain for which this must be done
+ * @min_freq : minimum frequency to return
+ * @cost_margin : allowed margin compared to min_freq, on the
+ * EM_COST_MARGIN_SCALE scale.
+ *
+ * Return: the chosen frequency, guaranteed to be at least as high as min_freq.
+ */
+static inline unsigned long em_pd_get_higher_freq(struct em_perf_domain *pd,
+ unsigned long min_freq, unsigned long cost_margin)
+{
+ unsigned long max_cost = 0;
+ struct em_cap_state *cs;
+ int i;
+
+ if (!pd)
+ return min_freq;
+
+ /* Compute the maximum allowed cost */
+ for (i = 0; i < pd->nr_cap_states; i++) {
+ cs = &pd->table[i];
+ if (cs->frequency >= min_freq) {
+ max_cost = cs->cost +
+ (cs->cost * cost_margin) / EM_COST_MARGIN_SCALE;
+ break;
+ }
+ }
+
+ /* Find the highest frequency that will not exceed the cost margin */
+ for (i = pd->nr_cap_states-1; i >= 0; i--) {
+ cs = &pd->table[i];
+ if (cs->cost <= max_cost)
+ return cs->frequency;
+ }
+
+ /*
+ * We should normally never reach here, unless min_freq was higher than
+ * the highest available frequency, which is not expected to happen.
+ */
+ return min_freq;
+}
+
+
#else
struct em_perf_domain {};
struct em_data_callback {};
@@ -182,6 +229,12 @@ static inline int em_pd_nr_cap_states(struct em_perf_domain *pd)
{
return 0;
}
+
+static inline unsigned long em_pd_get_higher_freq(struct em_perf_domain *pd,
+ unsigned long min_freq, unsigned long cost_margin)
+{
+ return min_freq;
+}
#endif
#endif
--
2.22.0
next prev parent reply other threads:[~2019-06-27 17:16 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-27 17:15 [RFC PATCH v2 0/5] sched/cpufreq: Make schedutil energy aware Douglas RAILLARD
2019-06-27 17:15 ` Douglas RAILLARD [this message]
2019-06-27 17:16 ` [RFC PATCH v2 2/5] sched/cpufreq: Attach perf domain to sugov policy Douglas RAILLARD
2019-06-27 17:16 ` [RFC PATCH v2 3/5] sched/cpufreq: Hook em_pd_get_higher_power() into get_next_freq() Douglas RAILLARD
2019-06-27 17:16 ` [RFC PATCH v2 4/5] sched/cpufreq: Introduce sugov_cpu_ramp_boost Douglas RAILLARD
2019-06-28 15:08 ` Patrick Bellasi
2019-06-27 17:16 ` [RFC PATCH v2 5/5] sched/cpufreq: Boost schedutil frequency ramp up Douglas RAILLARD
2019-07-02 15:44 ` [RFC PATCH v2 0/5] sched/cpufreq: Make schedutil energy aware Peter Zijlstra
2019-07-03 13:38 ` Douglas Raillard
2019-07-08 11:13 ` Patrick Bellasi
2019-07-08 13:49 ` Douglas Raillard
2019-07-02 15:51 ` Peter Zijlstra
2019-07-03 16:36 ` Douglas Raillard
2019-07-08 11:09 ` Patrick Bellasi
2019-07-08 13:46 ` Douglas Raillard
2019-07-09 10:37 ` Patrick Bellasi
2019-08-09 17:37 ` Douglas Raillard
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