libbpf-tools: add funcinterval

Signed-off-by: Feng Yang <[email protected]>

libbpf-tools/.gitignore

@@ -27,6 +27,7 @@
 /filetop
 /fsdist
 /fsslower
+/funcinterval
 /funclatency
 /futexctn
 /gethostlatency

libbpf-tools/Makefile

@@ -58,6 +58,7 @@ APPS = \
 	filetop \
 	fsdist \
 	fsslower \
+	funcinterval \
 	funclatency \
 	gethostlatency \
 	hardirqs \

libbpf-tools/funcinterval.bpf.c

@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2024 Feng Yang
+// Based on funcinterval.py from BCC by Edward Wu
+
+#include "vmlinux.h"
+#include <bpf/bpf_core_read.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "funcinterval.h"
+#include "maps.bpf.h"
+#include "bits.bpf.h"
+
+const volatile pid_t targ_pid = 0;
+const volatile bool targ_ms = false;
+
+static struct hist zero = {0};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, u64);
+} start SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, struct hist);
+} hists SEC(".maps");
+
+static int trace_func_entry(void *ctx)
+{
+	u64 pid_tgid = bpf_get_current_pid_tgid();
+	u32 index = 0, tgid = pid_tgid >> 32;
+	u64 *tsp, ts = bpf_ktime_get_ns(), delta, slot;
+	struct hist *histp;
+
+	if (targ_pid && tgid != targ_pid)
+		return 0;
+
+	tsp = bpf_map_lookup_elem(&start, &index);
+	if (tsp == 0)
+		goto out;
+
+	histp = bpf_map_lookup_or_try_init(&hists, &index, &zero);
+	if (!histp)
+		return 0;
+
+	delta = ts - *tsp;
+	if (targ_ms)
+		delta /= 1000000U;
+	else
+		delta /= 1000U;
+
+	// store as histogram
+	slot = log2l(delta);
+	if (slot >= MAX_SLOTS)
+		slot = MAX_SLOTS - 1;
+	__sync_fetch_and_add(&histp->slots[slot], 1);
+
+out:
+	bpf_map_update_elem(&start, &index, &ts, BPF_ANY);
+
+	return 0;
+}
+
+SEC("kprobe")
+int BPF_KPROBE(function_entry)
+{
+	return trace_func_entry(ctx);
+}
+
+SEC("tracepoint")
+int tracepoint_entry(void *ctx)
+{
+	return trace_func_entry(ctx);
+}
+
+SEC("uprobe")
+int BPF_KPROBE(function_uprobe_entry)
+{
+	return trace_func_entry(ctx);
+}
+
+char LICENSE[] SEC("license") = "GPL";