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Commit ab51dca9 authored by Connor O'Brien's avatar Connor O'Brien
Browse files

libtimeinstate: initialize current freq before starting tracking 



Currently, our BPF programs start with no knowledge of current CPU
frequency and tracking cannot begin for a cluster until a frequency
transition happens & makes this information available. On cuttlefish,
CPU frequency never changes, so tracking never starts & cuttlefish
can't be used for testing this feature.
To resolve this, pass the BPF programs initial frequency information
read from the scaling_cur_freq sysfs nodes.

Test: libtimeinstate_test passes on cuttlefish
Test: confirm that uid_time_in_state BPF map contains data on
cuttlefish
Bug: 138317993
Signed-off-by: default avatarConnor O'Brien <connoro@google.com>

Change-Id: I5b24c1311e1b58b73c7e32f41c2d99c5ab344549
parent c6f093ab

libs/cputimeinstate/cputimeinstate.cpp

+14 −1
Original line number Original line Diff line number Diff line
@@ -161,6 +161,17 @@ static bool attachTracepointProgram(const std::string &eventType, const std::str 
    return bpf_attach_tracepoint(prog_fd, eventType.c_str(), eventName.c_str()) >= 0;

    return bpf_attach_tracepoint(prog_fd, eventType.c_str(), eventName.c_str()) >= 0;

}

}





static std::optional<uint32_t> getPolicyFreqIdx(uint32_t policy) {

    auto path = StringPrintf("/sys/devices/system/cpu/cpufreq/policy%u/scaling_cur_freq",

                             gPolicyCpus[policy][0]);

    auto freqVec = readNumbersFromFile(path);

    if (!freqVec.has_value() || freqVec->size() != 1) return {};

    for (uint32_t idx = 0; idx < gPolicyFreqs[policy].size(); ++idx) {

        if ((*freqVec)[0] == gPolicyFreqs[policy][idx]) return idx + 1;

    }

    return {};

}



// Start tracking and aggregating data to be reported by getUidCpuFreqTimes and getUidsCpuFreqTimes.

// Start tracking and aggregating data to be reported by getUidCpuFreqTimes and getUidsCpuFreqTimes.

// Returns true on success, false otherwise.

// Returns true on success, false otherwise.

// Tracking is active only once a live process has successfully called this function; if the calling

// Tracking is active only once a live process has successfully called this function; if the calling
@@ -215,7 +226,9 @@ bool startTrackingUidTimes() { 
    unique_fd policyFreqIdxFd(bpf_obj_get_wronly(BPF_FS_PATH "map_time_in_state_policy_freq_idx_map"));

    unique_fd policyFreqIdxFd(bpf_obj_get_wronly(BPF_FS_PATH "map_time_in_state_policy_freq_idx_map"));

    if (policyFreqIdxFd < 0) return false;

    if (policyFreqIdxFd < 0) return false;

    for (uint32_t i = 0; i < gNPolicies; ++i) {

    for (uint32_t i = 0; i < gNPolicies; ++i) {

        if (writeToMapEntry(policyFreqIdxFd, &i, &zero, BPF_ANY)) return false;

        auto freqIdx = getPolicyFreqIdx(i);

        if (!freqIdx.has_value()) return false;

        if (writeToMapEntry(policyFreqIdxFd, &i, &(*freqIdx), BPF_ANY)) return false;

    }

    }





    gTracking = attachTracepointProgram("sched", "sched_switch") &&

    gTracking = attachTracepointProgram("sched", "sched_switch") &&