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: Connor O'Brien <connoro@google.com>
Change-Id: I5b24c1311e1b58b73c7e32f41c2d99c5ab344549
diff --git a/libs/cputimeinstate/cputimeinstate.cpp b/libs/cputimeinstate/cputimeinstate.cpp
index a03775b..58126dc 100644
--- a/libs/cputimeinstate/cputimeinstate.cpp
+++ b/libs/cputimeinstate/cputimeinstate.cpp
@@ -161,6 +161,17 @@
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.
// Returns true on success, false otherwise.
// Tracking is active only once a live process has successfully called this function; if the calling
@@ -215,7 +226,9 @@
unique_fd policyFreqIdxFd(bpf_obj_get_wronly(BPF_FS_PATH "map_time_in_state_policy_freq_idx_map"));
if (policyFreqIdxFd < 0) return false;
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") &&