bcc: Update criticalstat
Signed-off-by: Joel Fernandes <joel@linuxinternals.org>
diff --git a/bcc/criticalstat.py b/bcc/criticalstat.py
index 261bd3e..9a91a0e 100755
--- a/bcc/criticalstat.py
+++ b/bcc/criticalstat.py
@@ -91,6 +91,23 @@
BPF_PERCPU_ARRAY(isidle, u64, 1);
BPF_PERF_OUTPUT(events);
+/*
+ * In the below code we install tracepoint probes on preempt or
+ * IRQ disable/enable critical sections and idle events, the cases
+ * are combinations of 4 different states.
+ * The states are defined as:
+ * CSenter: A critical section has been entered. Either due to
+ * preempt disable or irq disable.
+ * CSexit: A critical section has been exited. Either due to
+ * preempt enable or irq enable.
+ * Ienter: The CPU has entered an idle state.
+ * Iexit: The CPU has exited an idle state.
+ *
+ * The scenario we are trying to detect is if there is an overlap
+ * between Critical sections and idle entry/exit. If there are any
+ * such cases, we avoid recording those critical sections since they
+ * are not worth while to record and just add noise.
+ */
TRACEPOINT_PROBE(power, cpu_idle)
{
int idx = 0;
@@ -111,11 +128,9 @@
// Mark CPU as actively within idle or not.
if (args->state < 100) {
- bpf_trace_printk(\"Setting idle\\n\");
val = 1;
isidle.update(&idx, &val);
} else {
- bpf_trace_printk(\"Resetting idle\\n\");
val = 0;
isidle.update(&idx, &val);
}
@@ -150,20 +165,17 @@
// Handle the case Ienter, CSenter, CSexit, Iexit
// Handle the case Ienter, CSenter, Iexit, CSexit
if (in_idle()) {
- bpf_trace_printk(\"disable: In idle, resetting\\n\");
reset_state();
return 0;
}
u64 ts = bpf_ktime_get_ns();
- bpf_trace_printk(\"Entered new section, setting time to %lu\\n\", (unsigned long)ts);
s.idle_skip = 0;
s.addr_offs[START_CALLER_OFF] = args->caller_offs;
s.addr_offs[START_PARENT_OFF] = args->parent_offs;
s.ts = ts;
s.active = 1;
- bpf_trace_printk(\"Finished storing\\n\", (unsigned long)ts);
sts.update(&idx, &s);
return 0;
@@ -178,15 +190,12 @@
// Handle the case CSenter, Ienter, CSexit, Iexit
// Handle the case Ienter, CSenter, CSexit, Iexit
if (in_idle()) {
- bpf_trace_printk(\"enable: In idle, resetting\\n\");
reset_state();
return 0;
}
- bpf_trace_printk(\"enable: start lookup\\n\");
stdp = sts.lookup(&idx);
- bpf_trace_printk(\"enable: start read\\n\");
bpf_probe_read(&std, sizeof(struct start_data), stdp);
// Handle the case Ienter, Csenter, Iexit, Csexit
@@ -201,18 +210,15 @@
return 0;
}
- bpf_trace_printk(\"enable: start gettime\\n\");
end_ts = bpf_ktime_get_ns();
start_ts = std.ts;
if (start_ts > end_ts) {
- bpf_trace_printk("ERROR: start < end\\n");
reset_state();
return 0;
}
diff = end_ts - start_ts;
- bpf_trace_printk(\"Exited section, diff is %lu\\n\", (unsigned long)diff);
if (diff < DURATION) {
reset_state();
@@ -232,10 +238,7 @@
data.stack_id = stack_traces.get_stackid(args, 0);
data.time = diff;
data.cpu = bpf_get_smp_processor_id();
- bpf_trace_printk(\"Large diff found: %lu\\n\", (unsigned long)diff);
events.perf_submit(args, &data, sizeof(data));
- } else {
- bpf_trace_printk("ERROR: Couldn't get process name\\n");
}
reset_state();
