libbpf-tools: add fsdist

fsdist is a multitool which show filesystem latency.
Currently we support btrfs/ext4/nfs/xfs filesystems.
It behaves the same as its counterpart in BCC tools
named btrfsdist.py/ext4dist.py/nfsdist.py/xfsdist.py

Signed-off-by: Hengqi Chen <[email protected]>

libbpf-tools/.gitignore

@@ -11,6 +11,7 @@
 /execsnoop
 /ext4dist
 /filelife
+/fsdist
 /funclatency
 /gethostlatency
 /hardirqs

libbpf-tools/Makefile

@@ -28,6 +28,7 @@ APPS = \
  execsnoop \
  ext4dist \
  filelife \
+ fsdist \
  funclatency \
  gethostlatency \
  hardirqs \

libbpf-tools/fsdist.bpf.c

@@ -0,0 +1,193 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+/* Copyright (c) 2021 Hengqi Chen */
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bits.bpf.h"
+#include "fsdist.h"
+
+#define MAX_ENTRIES 10240
+
+const volatile pid_t target_pid = 0;
+const volatile bool in_ms = false;
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, MAX_ENTRIES);
+ __type(key, __u32);
+ __type(value, __u64);
+} starts SEC(".maps");
+
+struct hist hists[MAX_OP] = {};
+
+static int probe_entry()
+{
+ __u64 pid_tgid = bpf_get_current_pid_tgid();
+ __u32 pid = pid_tgid >> 32;
+ __u32 tid = (__u32)pid_tgid;
+ __u64 ts;
+
+ if (target_pid && target_pid != pid)
+ return 0;
+
+ ts = bpf_ktime_get_ns();
+ bpf_map_update_elem(&starts, &tid, &ts, BPF_ANY);
+ return 0;
+}
+
+static int probe_return(enum fs_file_op op)
+{
+ __u64 pid_tgid = bpf_get_current_pid_tgid();
+ __u32 pid = pid_tgid >> 32;
+ __u32 tid = (__u32)pid_tgid;
+ __u64 ts = bpf_ktime_get_ns();
+ __u64 *tsp, slot;
+ __s64 delta;
+
+ tsp = bpf_map_lookup_elem(&starts, &tid);
+ if (!tsp)
+ return 0;
+
+ if (op >= MAX_OP)
+ goto cleanup;
+
+ delta = (__s64)(ts - *tsp);
+ if (delta < 0)
+ goto cleanup;
+
+ if (in_ms)
+ delta /= 1000000;
+ else
+ delta /= 1000;
+
+ slot = log2l(delta);
+ if (slot >= MAX_SLOTS)
+ slot = MAX_SLOTS - 1;
+ __sync_fetch_and_add(&hists[op].slots[slot], 1);
+
+cleanup:
+ bpf_map_delete_elem(&starts, &tid);
+ return 0;
+}
+
+SEC("kprobe/dummy_file_read")
+int BPF_KPROBE(file_read_entry)
+{
+ return probe_entry();
+}
+
+SEC("kretprobe/dummy_file_read")
+int BPF_KRETPROBE(file_read_exit)
+{
+ return probe_return(READ);
+}
+
+SEC("kprobe/dummy_file_write")
+int BPF_KPROBE(file_write_entry)
+{
+ return probe_entry();
+}
+
+SEC("kretprobe/dummy_file_write")
+int BPF_KRETPROBE(file_write_exit)
+{
+ return probe_return(WRITE);
+}
+
+SEC("kprobe/dummy_file_open")
+int BPF_KPROBE(file_open_entry)
+{
+ return probe_entry();
+}
+
+SEC("kretprobe/dummy_file_open")
+int BPF_KRETPROBE(file_open_exit)
+{
+ return probe_return(OPEN);
+}
+
+SEC("kprobe/dummy_file_sync")
+int BPF_KPROBE(file_sync_entry)
+{
+ return probe_entry();
+}
+
+SEC("kretprobe/dummy_file_sync")
+int BPF_KRETPROBE(file_sync_exit)
+{
+ return probe_return(FSYNC);
+}
+
+SEC("kprobe/dummy_getattr")
+int BPF_KPROBE(getattr_entry)
+{
+ return probe_entry();
+}
+
+SEC("kretprobe/dummy_getattr")
+int BPF_KRETPROBE(getattr_exit)
+{
+ return probe_return(GETATTR);
+}
+
+SEC("fentry/dummy_file_read")
+int BPF_PROG(file_read_fentry)
+{
+ return probe_entry();
+}
+
+SEC("fexit/dummy_file_read")
+int BPF_PROG(file_read_fexit)
+{
+ return probe_return(READ);
+}
+
+SEC("fentry/dummy_file_write")
+int BPF_PROG(file_write_fentry)
+{
+ return probe_entry();
+}
+
+SEC("fexit/dummy_file_write")
+int BPF_PROG(file_write_fexit)
+{
+ return probe_return(WRITE);
+}
+
+SEC("fentry/dummy_file_open")
+int BPF_PROG(file_open_fentry)
+{
+ return probe_entry();
+}
+
+SEC("fexit/dummy_file_open")
+int BPF_PROG(file_open_fexit)
+{
+ return probe_return(OPEN);
+}
+
+SEC("fentry/dummy_file_sync")
+int BPF_PROG(file_sync_fentry)
+{
+ return probe_entry();
+}
+
+SEC("fexit/dummy_file_sync")
+int BPF_PROG(file_sync_fexit)
+{
+ return probe_return(FSYNC);
+}
+
+SEC("fentry/dummy_getattr")
+int BPF_PROG(getattr_fentry)
+{
+ return probe_entry();
+}
+
+SEC("fexit/dummy_getattr")
+int BPF_PROG(getattr_fexit)
+{
+ return probe_return(GETATTR);
+}
+
+char LICENSE[] SEC("license") = "Dual BSD/GPL";