[RFC v1 16/16] perf kwork top: Add BPF-based statistics on softirq event support
From: Yang Jihong
Date: Sat Aug 12 2023 - 04:53:07 EST
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>
Signed-off-by: Yang Jihong <yangjihong1@xxxxxxxxxx>
---
tools/perf/util/bpf_kwork_top.c | 11 ++++
tools/perf/util/bpf_skel/kwork_top.bpf.c | 72 ++++++++++++++++++++++++
2 files changed, 83 insertions(+)
diff --git a/tools/perf/util/bpf_kwork_top.c b/tools/perf/util/bpf_kwork_top.c
index 3998bd2a938f..1a607b94f44d 100644
--- a/tools/perf/util/bpf_kwork_top.c
+++ b/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,
};
diff --git a/tools/perf/util/bpf_skel/kwork_top.bpf.c b/tools/perf/util/bpf_skel/kwork_top.bpf.c
index 9c7dc62386c7..84c15ccbab44 100644
--- a/tools/perf/util/bpf_skel/kwork_top.bpf.c
+++ b/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";
--
2.30.GIT