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module/sched: Return the correct maximum capacity

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The existing behaviour assumes that the cap_states file contains a list
of capacity|cost pairs, and attempts to return the maximum capacity by
selecting the value at the second last index of the list.

This assumption fails on some newer Qualcomm kernels where the
cap_states file contains a list of capacity|frequency|cost triplets.
Consequently, the maximum frequency would be erroneously returned
instead of the maximum capacity.

Fix the problem by dynamically calculating the index of the maximum
capacity by dividing the number of entries in cap_states by the value in
nr_cap_states.

---

For example, on a certain Snapdragon 845 device:

/proc/sys/kernel/sched_domain/cpu0/domain0/group0/energy/cap_states
        54 entries:

        CAP     FREQ    COST
        --------------------
        65	300000	12
        87	403200	17
        104	480000	21
        125	576000	27
        141	652800	31
        162	748800	37
        179     825600	42
        195	902400	47
        212	979200	52
        228	1056000	57
        245	1132800	62
        266	1228800	70
        286	1324800 78
        307	1420800	89
        328	1516800	103
        348	1612800	122
        365	1689600	141
        381	1766400	160

/proc/sys/kernel/sched_domain/cpu0/domain0/group0/energy/nr_cap_states
        18

Max capacity = 381 (third-last index)
This commit is contained in:
Josh Choo
2019-07-06 23:29:29 +08:00
committed by Marc Bonnici
parent f619f1dd07
commit a9b9938b0f
1 changed files with 4 additions and 1 deletions
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5
devlib/module/sched.py
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@@ -415,7 +415,10 @@ class SchedModule(Module):
sd = SchedProcFSData(self.target, cpu)
cap_states = sd.domains[0].groups[0].energy.cap_states
return int(cap_states.split('\t')[-2])
cap_states_list = cap_states.split('\t')
num_cap_states = sd.domains[0].groups[0].energy.nr_cap_states
max_cap_index = -1 * int(len(cap_states_list) / num_cap_states)
return int(cap_states_list[max_cap_index])
@memoized
def get_dmips_capacity(self, cpu):