commit c2541dc8fbd0b468fd80439786c00e5c14838ce3
author Connor O'Brien <connoro@google.com> Thu Jun 06 17:36:52 2019 -0700
committer Connor O'Brien <connoro@google.com> Mon Jul 29 12:19:22 2019 -0700
tree 54342532218f13c22df442f26171ce5d07009d42
parent 24e737a0b339a2f90d326b0d29a44b3ae8e57a6f

time_in_state: support cpufreq fast switching

On devices that support fast cpufreq switching, cpu_freq trace events
are triggered once per cluster rather than once per cpu. By storing
cpu to cluster and cluster to freq mappings, we can obtain the correct
freq for a cpu regardless of whether fast switching is in use.

Test: libtimeinstate_test passes
Change-Id: Ia985ff61193985042223f8ee037ab4294edc2bbf
Signed-off-by: Connor O'Brien <connoro@google.com>

time_in_state.c

diff --git a/time_in_state.c b/time_in_state.c
index 618ebd4..b91de5e 100644
--- a/time_in_state.c
+++ b/time_in_state.c
@@ -24,8 +24,8 @@
 DEFINE_BPF_MAP(uid_times_map, PERCPU_HASH, time_key, uint64_t, 10240)
 DEFINE_BPF_MAP(cpu_last_update_map, PERCPU_ARRAY, uint32_t, uint64_t, 1)
 
-/* Assume max of 1024 CPUs */
-DEFINE_BPF_MAP(cpu_freq_map, ARRAY, uint32_t, uint32_t, 1024)
+DEFINE_BPF_MAP(cpu_policy_map, ARRAY, uint32_t, uint32_t, 1024)
+DEFINE_BPF_MAP(policy_freq_map, ARRAY, uint32_t, uint32_t, 1024)
 
 struct switch_args {
     unsigned long long ignore;
@@ -46,18 +46,24 @@
     uint64_t old_last = *last;
     uint64_t time = bpf_ktime_get_ns();
     *last = time;
+
+    if (!args->prev_pid || !old_last) return 0;
+
     uint32_t cpu = bpf_get_smp_processor_id();
-    uint32_t* freq = bpf_cpu_freq_map_lookup_elem(&cpu);
-    if (args->prev_pid && old_last && freq && *freq) {
-        uint32_t uid = bpf_get_current_uid_gid();
-        time_key key = {.uid = uid, .freq = *freq};
-        uint64_t* tot_time = bpf_uid_times_map_lookup_elem(&key);
-        uint64_t delta = time - old_last;
-        if (!tot_time)
-            bpf_uid_times_map_update_elem(&key, &delta, BPF_ANY);
-        else
-            *tot_time += delta;
-    }
+    uint32_t* policyp = bpf_cpu_policy_map_lookup_elem(&cpu);
+    if (!policyp) return 0;
+    uint32_t policy = *policyp;
+    uint32_t* freq = bpf_policy_freq_map_lookup_elem(&policy);
+    if (!freq || !*freq) return 0;
+
+    uint32_t uid = bpf_get_current_uid_gid();
+    time_key key = {.uid = uid, .freq = *freq};
+    uint64_t* tot_time = bpf_uid_times_map_lookup_elem(&key);
+    uint64_t delta = time - old_last;
+    if (!tot_time)
+        bpf_uid_times_map_update_elem(&key, &delta, BPF_ANY);
+    else
+        *tot_time += delta;
     return 0;
 }
 
@@ -71,7 +77,10 @@
 int tp_cpufreq(struct cpufreq_args* args) {
     uint32_t cpu = args->cpu_id;
     unsigned int new = args->state;
-    bpf_cpu_freq_map_update_elem(&cpu, &new, BPF_ANY);
+    uint32_t* policyp = bpf_cpu_policy_map_lookup_elem(&cpu);
+    if (!policyp) return 0;
+    uint32_t policy = *policyp;
+    bpf_policy_freq_map_update_elem(&policy, &new, BPF_ANY);
     return 0;
 }