Merge pull request #402 from mcaleavya/master

Migrated filelife to bpf_perf_event

man/man8/filelife.8

@@ -13,6 +13,10 @@ This works by tracing the kernel vfs_create() and vfs_delete() functions using
 dynamic tracing, and will need updating to match any changes to these
 functions.
 
+This makes use of a Linux 4.5 feature (bpf_perf_event_output());
+for kernels older than 4.5, see the version under tools/old,
+which uses an older mechanism.
+
 Since this uses BPF, only the root user can use this tool.
 .SH REQUIREMENTS
 CONFIG_BPF and bcc.

tools/filelife.py

@@ -15,11 +15,13 @@
 # Licensed under the Apache License, Version 2.0 (the "License")
 #
 # 08-Feb-2015   Brendan Gregg   Created this.
+# 17-Feb-2016   Allan McAleavy updated for BPF_PERF_OUTPUT
 
 from __future__ import print_function
 from bcc import BPF
 import argparse
 from time import strftime
+import ctypes as ct
 
 # arguments
 examples = """examples:
@@ -39,8 +41,17 @@ debug = 0
 bpf_text = """
 #include <uapi/linux/ptrace.h>
 #include <linux/fs.h>
+#include <linux/sched.h>
+
+struct data_t {
+    u32 pid;
+    u64 delta;
+    char comm[TASK_COMM_LEN];
+    char fname[DNAME_INLINE_LEN];
+};
 
 BPF_HASH(birth, struct dentry *);
+BPF_PERF_OUTPUT(events);
 
 // trace file creation time
 int trace_create(struct pt_regs *ctx, struct inode *dir, struct dentry *dentry)
@@ -57,7 +68,9 @@ int trace_create(struct pt_regs *ctx, struct inode *dir, struct dentry *dentry)
 // trace file deletion and output details
 int trace_unlink(struct pt_regs *ctx, struct inode *dir, struct dentry *dentry)
 {
+    struct data_t data = {};
     u32 pid = bpf_get_current_pid_tgid();
+
     FILTER
 
     u64 *tsp, delta;
@@ -65,17 +78,36 @@ int trace_unlink(struct pt_regs *ctx, struct inode *dir, struct dentry *dentry)
     if (tsp == 0) {
         return 0;   // missed create
     }
+
     delta = (bpf_ktime_get_ns() - *tsp) / 1000000;
     birth.delete(&dentry);
 
     if (dentry->d_iname[0] == 0)
         return 0;
 
-    bpf_trace_printk("%d %s\\n", delta, dentry->d_iname);
+    if (bpf_get_current_comm(&data.comm, sizeof(data.comm)) == 0) {
+        data.pid = pid;
+        data.delta = delta;
+        bpf_probe_read(&data.fname, sizeof(data.fname), dentry->d_iname);
+    }
+
+    events.perf_submit(ctx, &data, sizeof(data));
 
     return 0;
 }
 """
+
+TASK_COMM_LEN = 16            # linux/sched.h
+DNAME_INLINE_LEN = 255        # linux/dcache.h
+
+class Data(ct.Structure):
+    _fields_ = [
+        ("pid", ct.c_ulonglong),
+        ("delta", ct.c_ulonglong),
+        ("comm", ct.c_char * TASK_COMM_LEN),
+        ("fname", ct.c_char * DNAME_INLINE_LEN)
+    ]
+
 if args.pid:
     bpf_text = bpf_text.replace('FILTER',
         'if (pid != %s) { return 0; }' % args.pid)
@@ -92,13 +124,12 @@ b.attach_kprobe(event="vfs_unlink", fn_name="trace_unlink")
 # header
 print("%-8s %-6s %-16s %-7s %s" % ("TIME", "PID", "COMM", "AGE(s)", "FILE"))
 
-start_ts = 0
+# process event
+def print_event(cpu, data, size):
+    event = ct.cast(data, ct.POINTER(Data)).contents
+    print("%-8s %-6d %-16s %-7.2f %s" % (strftime("%H:%M:%S"), event.pid,
+        event.comm, float(event.delta) / 1000, event.fname))
 
-# format output
+b["events"].open_perf_buffer(print_event)
 while 1:
-    (task, pid, cpu, flags, ts, msg) = b.trace_fields()
-    (delta, filename) = msg.split(" ", 1)
-
-    # print columns
-    print("%-8s %-6d %-16s %-7.2f %s" % (strftime("%H:%M:%S"), pid, task,
-        float(delta) / 1000, filename))
+    b.kprobe_poll()

tools/old/filelife.py

+#!/usr/bin/python
+# @lint-avoid-python-3-compatibility-imports
+#
+# filelife    Trace the lifespan of short-lived files.
+#             For Linux, uses BCC, eBPF. Embedded C.
+#
+# This traces the creation and deletion of files, providing information
+# on who deleted the file, the file age, and the file name. The intent is to
+# provide information on short-lived files, for debugging or performance
+# analysis.
+#
+# USAGE: filelife [-h] [-p PID]
+#
+# Copyright 2016 Netflix, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+#
+# 08-Feb-2015   Brendan Gregg   Created this.
+
+from __future__ import print_function
+from bcc import BPF
+import argparse
+from time import strftime
+
+# arguments
+examples = """examples:
+    ./filelife           # trace all stat() syscalls
+    ./filelife -p 181    # only trace PID 181
+"""
+parser = argparse.ArgumentParser(
+    description="Trace stat() syscalls",
+    formatter_class=argparse.RawDescriptionHelpFormatter,
+    epilog=examples)
+parser.add_argument("-p", "--pid",
+    help="trace this PID only")
+args = parser.parse_args()
+debug = 0
+
+# define BPF program
+bpf_text = """
+#include <uapi/linux/ptrace.h>
+#include <linux/fs.h>
+
+BPF_HASH(birth, struct dentry *);
+
+// trace file creation time
+int trace_create(struct pt_regs *ctx, struct inode *dir, struct dentry *dentry)
+{
+    u32 pid = bpf_get_current_pid_tgid();
+    FILTER
+
+    u64 ts = bpf_ktime_get_ns();
+    birth.update(&dentry, &ts);
+
+    return 0;
+};
+
+// trace file deletion and output details
+int trace_unlink(struct pt_regs *ctx, struct inode *dir, struct dentry *dentry)
+{
+    u32 pid = bpf_get_current_pid_tgid();
+    FILTER
+
+    u64 *tsp, delta;
+    tsp = birth.lookup(&dentry);
+    if (tsp == 0) {
+        return 0;   // missed create
+    }
+    delta = (bpf_ktime_get_ns() - *tsp) / 1000000;
+    birth.delete(&dentry);
+
+    if (dentry->d_iname[0] == 0)
+        return 0;
+
+    bpf_trace_printk("%d %s\\n", delta, dentry->d_iname);
+
+    return 0;
+}
+"""
+if args.pid:
+    bpf_text = bpf_text.replace('FILTER',
+        'if (pid != %s) { return 0; }' % args.pid)
+else:
+    bpf_text = bpf_text.replace('FILTER', '')
+if debug:
+    print(bpf_text)
+
+# initialize BPF
+b = BPF(text=bpf_text)
+b.attach_kprobe(event="vfs_create", fn_name="trace_create")
+b.attach_kprobe(event="vfs_unlink", fn_name="trace_unlink")
+
+# header
+print("%-8s %-6s %-16s %-7s %s" % ("TIME", "PID", "COMM", "AGE(s)", "FILE"))
+
+start_ts = 0
+
+# format output
+while 1:
+    (task, pid, cpu, flags, ts, msg) = b.trace_fields()
+    (delta, filename) = msg.split(" ", 1)
+
+    # print columns
+    print("%-8s %-6d %-16s %-7.2f %s" % (strftime("%H:%M:%S"), pid, task,
+        float(delta) / 1000, filename))