perf kwork top: Add BPF-based statistics on softirq event support

Use BPF to collect statistics on softirq events based on perf BPF skeletons.

Example usage:

  # perf kwork top -b
  Starting trace, Hit <Ctrl+C> to stop and report
  ^C
  Total  : 135445.704 ms, 8 cpus
  %Cpu(s):  28.35% id,   0.00% hi,   0.25% si
  %Cpu0   [||||||||||||||||||||            69.85%]
  %Cpu1   [||||||||||||||||||||||          74.10%]
  %Cpu2   [|||||||||||||||||||||           71.18%]
  %Cpu3   [||||||||||||||||||||            69.61%]
  %Cpu4   [||||||||||||||||||||||          74.05%]
  %Cpu5   [||||||||||||||||||||            69.33%]
  %Cpu6   [||||||||||||||||||||            69.71%]
  %Cpu7   [||||||||||||||||||||||          73.77%]

        PID     SPID    %CPU           RUNTIME  COMMMAND
    -------------------------------------------------------------
          0        0   30.43       5271.005 ms  [swapper/5]
          0        0   30.17       5226.644 ms  [swapper/3]
          0        0   30.08       5210.257 ms  [swapper/6]
          0        0   29.89       5177.177 ms  [swapper/0]
          0        0   28.51       4938.672 ms  [swapper/2]
          0        0   25.93       4223.464 ms  [swapper/7]
          0        0   25.69       4181.411 ms  [swapper/4]
          0        0   25.63       4173.804 ms  [swapper/1]
      16665    16265    2.16        360.600 ms  sched-messaging
      16537    16265    2.05        356.275 ms  sched-messaging
      16503    16265    2.01        343.063 ms  sched-messaging
      16424    16265    1.97        336.876 ms  sched-messaging
      16580    16265    1.94        323.658 ms  sched-messaging
      16515    16265    1.92        321.616 ms  sched-messaging
      16659    16265    1.91        325.538 ms  sched-messaging
      16634    16265    1.88        327.766 ms  sched-messaging
      16454    16265    1.87        326.843 ms  sched-messaging
      16382    16265    1.87        322.591 ms  sched-messaging
      16642    16265    1.86        320.506 ms  sched-messaging
      16582    16265    1.86        320.164 ms  sched-messaging
      16315    16265    1.86        326.872 ms  sched-messaging
      16637    16265    1.85        323.766 ms  sched-messaging
      16506    16265    1.82        311.688 ms  sched-messaging
      16512    16265    1.81        304.643 ms  sched-messaging
      16560    16265    1.80        314.751 ms  sched-messaging
      16320    16265    1.80        313.405 ms  sched-messaging
      16442    16265    1.80        314.403 ms  sched-messaging
      16626    16265    1.78        295.380 ms  sched-messaging
      16600    16265    1.77        309.444 ms  sched-messaging
      16550    16265    1.76        301.161 ms  sched-messaging
      16525    16265    1.75        296.560 ms  sched-messaging
      16314    16265    1.75        298.338 ms  sched-messaging
      16595    16265    1.74        304.390 ms  sched-messaging
      16555    16265    1.74        287.564 ms  sched-messaging
      16520    16265    1.74        295.734 ms  sched-messaging
      16507    16265    1.73        293.956 ms  sched-messaging
      16593    16265    1.72        296.443 ms  sched-messaging
      16531    16265    1.72        299.950 ms  sched-messaging
      16281    16265    1.72        301.339 ms  sched-messaging
  <SNIP>
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Sandipan Das <sandipan.das@amd.com>
Link: https://lore.kernel.org/r/20230812084917.169338-17-yangjihong1@huawei.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/bpf_kwork_top.c

@@ -89,6 +89,16 @@ static struct kwork_class_bpf kwork_irq_bpf = {
 	.load_prepare = irq_load_prepare,
 };
 
+static void softirq_load_prepare(void)
+{
+	bpf_program__set_autoload(skel->progs.on_softirq_entry, true);
+	bpf_program__set_autoload(skel->progs.on_softirq_exit, true);
+}
+
+static struct kwork_class_bpf kwork_softirq_bpf = {
+	.load_prepare = softirq_load_prepare,
+};
+
 static void sched_load_prepare(void)
 {
 	bpf_program__set_autoload(skel->progs.on_switch, true);
@@ -101,6 +111,7 @@ static struct kwork_class_bpf kwork_sched_bpf = {
 static struct kwork_class_bpf *
 kwork_class_bpf_supported_list[KWORK_CLASS_MAX] = {
 	[KWORK_CLASS_IRQ]	= &kwork_irq_bpf,
+	[KWORK_CLASS_SOFTIRQ]	= &kwork_softirq_bpf,
 	[KWORK_CLASS_SCHED]	= &kwork_sched_bpf,
 };
 

tools/perf/util/bpf_skel/kwork_top.bpf.c

@@ -263,4 +263,76 @@ int on_irq_handler_exit(u64 *cxt)
 	return 0;
 }
 
+SEC("tp_btf/softirq_entry")
+int on_softirq_entry(u64 *cxt)
+{
+	struct task_struct *task;
+
+	if (!enabled)
+		return 0;
+
+	__u32 cpu = bpf_get_smp_processor_id();
+
+	if (cpu_is_filtered(cpu))
+		return 0;
+
+	__u64 ts = bpf_ktime_get_ns();
+
+	task = (struct task_struct *)bpf_get_current_task();
+	if (!task)
+		return 0;
+
+	struct work_key key = {
+		.type = KWORK_CLASS_SOFTIRQ,
+		.pid = BPF_CORE_READ(task, pid),
+		.task_p = (__u64)task,
+	};
+
+	struct time_data data = {
+		.timestamp = ts,
+	};
+
+	bpf_map_update_elem(&kwork_top_irq_time, &key, &data, BPF_ANY);
+
+	return 0;
+}
+
+SEC("tp_btf/softirq_exit")
+int on_softirq_exit(u64 *cxt)
+{
+	__u64 delta;
+	struct task_struct *task;
+	struct time_data *pelem;
+
+	if (!enabled)
+		return 0;
+
+	__u32 cpu = bpf_get_smp_processor_id();
+
+	if (cpu_is_filtered(cpu))
+		return 0;
+
+	__u64 ts = bpf_ktime_get_ns();
+
+	task = (struct task_struct *)bpf_get_current_task();
+	if (!task)
+		return 0;
+
+	struct work_key key = {
+		.type = KWORK_CLASS_SOFTIRQ,
+		.pid = BPF_CORE_READ(task, pid),
+		.task_p = (__u64)task,
+	};
+
+	pelem = bpf_map_lookup_elem(&kwork_top_irq_time, &key);
+	if (pelem)
+		delta = ts - pelem->timestamp;
+	else
+		delta = ts - from_timestamp;
+
+	update_work(&key, delta);
+
+	return 0;
+}
+
 char LICENSE[] SEC("license") = "Dual BSD/GPL";