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Commit ac81ea3e authored by Vincent Donnefort's avatar Vincent Donnefort Committed by Lee Jones
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BACKPORT: PM: EM: Fix inefficient states detection 



Currently, a debug message is printed if an inefficient state is detected
in the Energy Model. Unfortunately, it won't detect if the first state is
inefficient or if two successive states are. Fix this behavior.

Bug: 254441685
Fixes: 27871f7a8a34 (PM: Introduce an Energy Model management framework)
Signed-off-by: default avatarVincent Donnefort <vincent.donnefort@arm.com>
Reviewed-by: default avatarQuentin Perret <qperret@google.com>
Reviewed-by: default avatarLukasz Luba <lukasz.luba@arm.com>
Reviewed-by: default avatarMatthias Kaehlcke <mka@chromium.org>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
(cherry picked from commit aa1a43262ad5df010768f69530fa179ff81651d3)
Signed-off-by: default avatarLee Jones <joneslee@google.com>
Change-Id: Id3a8431065a504be40ab009cae3cc105fa6a6ae6
parent 097a5031

kernel/power/energy_model.c

+8 −15
Original line number Diff line number Diff line
@@ -81,8 +81,7 @@ static void em_debug_create_pd(struct em_perf_domain *pd, int cpu) {} 
static struct em_perf_domain *em_create_pd(cpumask_t *span, int nr_states,

						struct em_data_callback *cb)

{

	unsigned long opp_eff, prev_opp_eff = ULONG_MAX;

	unsigned long power, freq, prev_freq = 0;

	unsigned long power, freq, prev_freq = 0, prev_cost = ULONG_MAX;

	int i, ret, cpu = cpumask_first(span);

	struct em_cap_state *table;

	struct em_perf_domain *pd;
@@ -132,27 +131,21 @@ static struct em_perf_domain *em_create_pd(cpumask_t *span, int nr_states, 


		table[i].power = power;

		table[i].frequency = prev_freq = freq;



		/*

		 * The hertz/watts efficiency ratio should decrease as the

		 * frequency grows on sane platforms. But this isn't always

		 * true in practice so warn the user if a higher OPP is more

		 * power efficient than a lower one.

		 */

		opp_eff = freq / power;

		if (opp_eff >= prev_opp_eff)

			pr_warn("pd%d: hertz/watts ratio non-monotonically decreasing: em_cap_state %d >= em_cap_state%d\n",

					cpu, i, i - 1);

		prev_opp_eff = opp_eff;

	}



	/* Compute the cost of each capacity_state. */

	fmax = (u64) table[nr_states - 1].frequency;

	for (i = 0; i < nr_states; i++) {

	for (i = nr_states - 1; i >= 0; i--) {

		unsigned long power_res = em_scale_power(table[i].power);



		table[i].cost = div64_u64(fmax * power_res,

					  table[i].frequency);

		if (table[i].cost >= prev_cost) {

			pr_warn("pd%d: EM: OPP:%lu is inefficient\n",

				cpu, table[i].frequency);

		} else {

			prev_cost = table[i].cost;

		}

	}



	pd->table = table;