fixup: apply feedback

Signed-off-by: Florian Lehner <florian.lehner@elastic.co>

cli_flags.go

@@ -63,9 +63,9 @@ var (
 		"on agent startup, but not periodically."
 	sendErrorFramesHelp = "Send error frames (devfiler only, breaks Kibana)"
 	offCPUThresholdHelp = fmt.Sprintf("If set to a value between 1 and %d will enable "+
-		"off cpu profiling: Every time an off-cpu entry point is hit, a random number between "+
-		"0 and %d is chosen. If the given threshold is greater than this random number, the off "+
-		"cpu trace is collected and reported.",
+		"off-cpu profiling: Every time an off-cpu entry point is hit, a random number between "+
+		"0 and %d is chosen. If the given threshold is greater than this random number, the "+
+		"off-cpu trace is collected and reported.",
 		tracer.OffCPUThresholdMax-1, tracer.OffCPUThresholdMax-1)
 )
 

libpf/symbol.go

@@ -90,7 +90,7 @@ func (symmap *SymbolMap) LookupSymbolByPrefix(prefix string) (*Symbol, error) {
 			return sym, nil
 		}
 	}
-	return nil, fmt.Errorf("no symbol not present that starts with '%s' in map", prefix)
+	return nil, fmt.Errorf("no symbol present that starts with '%s'", prefix)
 }
 
 // LookupSymbolAddress returns the address of a symbol.

support/ebpf/off_cpu.ebpf.c

@@ -43,7 +43,8 @@ int tracepoint__sched_switch(void *ctx) {
   u64 ts = bpf_ktime_get_ns();
 
   if (bpf_map_update_elem(&profile_off_cpu, &pid_tgid, &ts, BPF_ANY)<0){
-      return 0;
+    DEBUG_PRINT("Failed to record sched_switch event entry");
+	  return 0;
   }
 
   return 0;
@@ -78,9 +79,8 @@ int finish_task_switch(struct pt_regs *ctx) {
     return 0;
   }
 
-  DEBUG_PRINT("==== finish_task_switch ====");
-
   u64 diff = ts - *start_ts;
+  DEBUG_PRINT("==== finish_task_switch ====");
 
   return collect_trace(ctx, TRACE_OFF_CPU, pid, tid, ts, diff);
 }

support/ebpf/types.h

@@ -547,8 +547,7 @@ typedef struct Trace {
   // origin indicates the source of the trace.
   TraceOrigin origin;
 
-  // Time in nanosecond for off-cpu profiling,
-  // for how long the trace was off cpu.
+  // offtime stores the nanoseconds that the trace was off-cpu for.
   u64 offtime;
 
   // The frames of the stack trace.