libtimeinstate: clear stale map values in startTrackingUidTimes()
If system_server is killed and restarted after attaching programs to
tracepoints, the values in several maps will become stale before the
programs are re-attached, leading to errors. For example, stale times
in the cpu_last_update map will cause the entire time since the
sched_switch program was detached to be attributed to the first task
to switch out after reattach.
To mitigate this, zero out all potentially stale map entries before
attaching any bpf programs to tracepoints.
Also, give the map fds in startTrackingUidTimes() more descriptive
names now that there are six different maps being opened.
Bug: 138317993
Test: libtimeinstate_test passes after restarting attaching process
Change-Id: I786d728108ca40575047c5c22c76034d05b6e2c2
Signed-off-by: Connor O'Brien <connoro@google.com>
diff --git a/libs/cputimeinstate/cputimeinstate.cpp b/libs/cputimeinstate/cputimeinstate.cpp
index 1590e2c..7b7a7e3 100644
--- a/libs/cputimeinstate/cputimeinstate.cpp
+++ b/libs/cputimeinstate/cputimeinstate.cpp
@@ -163,17 +163,17 @@
bool startTrackingUidTimes() {
if (!initGlobals()) return false;
- unique_fd fd(bpf_obj_get_wronly(BPF_FS_PATH "map_time_in_state_cpu_policy_map"));
- if (fd < 0) return false;
+ unique_fd cpuPolicyFd(bpf_obj_get_wronly(BPF_FS_PATH "map_time_in_state_cpu_policy_map"));
+ if (cpuPolicyFd < 0) return false;
for (uint32_t i = 0; i < gPolicyCpus.size(); ++i) {
for (auto &cpu : gPolicyCpus[i]) {
- if (writeToMapEntry(fd, &cpu, &i, BPF_ANY)) return false;
+ if (writeToMapEntry(cpuPolicyFd, &cpu, &i, BPF_ANY)) return false;
}
}
- unique_fd fd2(bpf_obj_get_wronly(BPF_FS_PATH "map_time_in_state_freq_to_idx_map"));
- if (fd2 < 0) return false;
+ unique_fd freqToIdxFd(bpf_obj_get_wronly(BPF_FS_PATH "map_time_in_state_freq_to_idx_map"));
+ if (freqToIdxFd < 0) return false;
freq_idx_key_t key;
for (uint32_t i = 0; i < gNPolicies; ++i) {
key.policy = i;
@@ -183,10 +183,32 @@
// The uid_times map still uses 0-based indexes, and the sched_switch program handles
// conversion between them, so this does not affect our map reading code.
uint32_t idx = j + 1;
- if (writeToMapEntry(fd2, &key, &idx, BPF_ANY)) return false;
+ if (writeToMapEntry(freqToIdxFd, &key, &idx, BPF_ANY)) return false;
}
}
+ unique_fd cpuLastUpdateFd(bpf_obj_get_wronly(BPF_FS_PATH "map_time_in_state_cpu_last_update_map"));
+ if (cpuLastUpdateFd < 0) return false;
+ std::vector<uint64_t> zeros(get_nprocs_conf(), 0);
+ uint32_t zero = 0;
+ if (writeToMapEntry(cpuLastUpdateFd, &zero, zeros.data(), BPF_ANY)) return false;
+
+ unique_fd nrActiveFd(bpf_obj_get_wronly(BPF_FS_PATH "map_time_in_state_nr_active_map"));
+ if (nrActiveFd < 0) return false;
+ if (writeToMapEntry(nrActiveFd, &zero, &zero, BPF_ANY)) return false;
+
+ unique_fd policyNrActiveFd(bpf_obj_get_wronly(BPF_FS_PATH "map_time_in_state_policy_nr_active_map"));
+ if (policyNrActiveFd < 0) return false;
+ for (uint32_t i = 0; i < gNPolicies; ++i) {
+ if (writeToMapEntry(policyNrActiveFd, &i, &zero, BPF_ANY)) return false;
+ }
+
+ 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;
+ }
+
return attachTracepointProgram("sched", "sched_switch") &&
attachTracepointProgram("power", "cpu_frequency");
}