add new topics (#132)

* add goroutine text

* update

* fix funclatency

* update doc

* update about nginx

* update nginx

* u[date co

* fix compile

src/33-funclatency/funclatency.bpf.c

@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Google LLC. */
+#include "vmlinux.h"
+#include <bpf/bpf_core_read.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "funclatency.h"
+#include "bits.bpf.h"
+
+const volatile pid_t targ_tgid = 0;
+const volatile int units = 0;
+
+/* key: pid.  value: start time */
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(max_entries, MAX_PIDS);
+	__type(key, u32);
+	__type(value, u64);
+} starts SEC(".maps");
+
+__u32 hist[MAX_SLOTS] = {};
+
+static void entry(void)
+{
+	u64 id = bpf_get_current_pid_tgid();
+	u32 tgid = id >> 32;
+	u32 pid = id;
+	u64 nsec;
+
+	if (targ_tgid && targ_tgid != tgid)
+		return;
+	nsec = bpf_ktime_get_ns();
+	bpf_map_update_elem(&starts, &pid, &nsec, BPF_ANY);
+}
+
+SEC("kprobe/dummy_kprobe")
+int BPF_KPROBE(dummy_kprobe)
+{
+	entry();
+	return 0;
+}
+
+static void exit(void)
+{
+	u64 *start;
+	u64 nsec = bpf_ktime_get_ns();
+	u64 id = bpf_get_current_pid_tgid();
+	u32 pid = id;
+	u64 slot, delta;
+
+	start = bpf_map_lookup_elem(&starts, &pid);
+	if (!start)
+		return;
+
+	delta = nsec - *start;
+
+	switch (units) {
+	case USEC:
+		delta /= 1000;
+		break;
+	case MSEC:
+		delta /= 1000000;
+		break;
+	}
+
+	slot = log2l(delta);
+	if (slot >= MAX_SLOTS)
+		slot = MAX_SLOTS - 1;
+	__sync_fetch_and_add(&hist[slot], 1);
+}
+
+SEC("kretprobe/dummy_kretprobe")
+int BPF_KRETPROBE(dummy_kretprobe)
+{
+	exit();
+	return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";