From: Vincent Donnefort vincent.donnefort@arm.com
[ Upstream commit aa1a43262ad5df010768f69530fa179ff81651d3 ]
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.
Fixes: 27871f7a8a34 (PM: Introduce an Energy Model management framework) Signed-off-by: Vincent Donnefort vincent.donnefort@arm.com Reviewed-by: Quentin Perret qperret@google.com Reviewed-by: Lukasz Luba lukasz.luba@arm.com Reviewed-by: Matthias Kaehlcke mka@chromium.org Acked-by: Viresh Kumar viresh.kumar@linaro.org Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/power/energy_model.c | 23 ++++++++--------------- 1 file changed, 8 insertions(+), 15 deletions(-)
diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c index a332ccd829e24..97e62469a6b32 100644 --- a/kernel/power/energy_model.c +++ b/kernel/power/energy_model.c @@ -107,8 +107,7 @@ static void em_debug_remove_pd(struct device *dev) {} static int em_create_perf_table(struct device *dev, struct em_perf_domain *pd, 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; struct em_perf_state *table; int i, ret; u64 fmax; @@ -153,27 +152,21 @@ static int em_create_perf_table(struct device *dev, struct em_perf_domain *pd,
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) - dev_dbg(dev, "EM: hertz/watts ratio non-monotonically decreasing: em_perf_state %d >= em_perf_state%d\n", - i, i - 1); - prev_opp_eff = opp_eff; }
/* Compute the cost of each performance 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) { + dev_dbg(dev, "EM: OPP:%lu is inefficient\n", + table[i].frequency); + } else { + prev_cost = table[i].cost; + } }
pd->table = table;