Update opensnoop to filter by PID and TID (#739)
* Use real PID instead of TID in opensnoop
* Replaced -t for timestamp with -T
* Support TID as well as PID
* Update opensnoop example
* Update man
* Added missing documentation re -n option
* Minor: styling
diff --git a/tools/opensnoop.py b/tools/opensnoop.py
index f2bac4b..0c2b9b5 100755
--- a/tools/opensnoop.py
+++ b/tools/opensnoop.py
@@ -4,13 +4,14 @@
# opensnoop Trace open() syscalls.
# For Linux, uses BCC, eBPF. Embedded C.
#
-# USAGE: opensnoop [-h] [-t] [-x] [-p PID]
+# USAGE: opensnoop [-h] [-T] [-x] [-p PID] [-t TID] [-n NAME]
#
# Copyright (c) 2015 Brendan Gregg.
# Licensed under the Apache License, Version 2.0 (the "License")
#
# 17-Sep-2015 Brendan Gregg Created this.
-# 29-Apr-2016 Allan McAleavy updated for BPF_PERF_OUTPUT
+# 29-Apr-2016 Allan McAleavy Updated for BPF_PERF_OUTPUT.
+# 08-Oct-2016 Dina Goldshtein Support filtering by PID and TID.
from __future__ import print_function
from bcc import BPF
@@ -20,21 +21,24 @@
# arguments
examples = """examples:
./opensnoop # trace all open() syscalls
- ./opensnoop -t # include timestamps
+ ./opensnoop -T # include timestamps
./opensnoop -x # only show failed opens
./opensnoop -p 181 # only trace PID 181
+ ./opensnoop -t 123 # only trace TID 123
./opensnoop -n main # only print process names containing "main"
"""
parser = argparse.ArgumentParser(
description="Trace open() syscalls",
formatter_class=argparse.RawDescriptionHelpFormatter,
epilog=examples)
-parser.add_argument("-t", "--timestamp", action="store_true",
+parser.add_argument("-T", "--timestamp", action="store_true",
help="include timestamp on output")
parser.add_argument("-x", "--failed", action="store_true",
help="only show failed opens")
parser.add_argument("-p", "--pid",
help="trace this PID only")
+parser.add_argument("-t", "--tid",
+ help="trace this TID only")
parser.add_argument("-n", "--name",
help="only print process names containing this name")
args = parser.parse_args()
@@ -47,35 +51,36 @@
#include <linux/sched.h>
struct val_t {
- u32 pid;
+ u64 id;
u64 ts;
char comm[TASK_COMM_LEN];
const char *fname;
};
struct data_t {
- u32 pid;
+ u64 id;
u64 ts;
int ret;
char comm[TASK_COMM_LEN];
char fname[NAME_MAX];
};
-BPF_HASH(args_filename, u32, const char *);
-BPF_HASH(infotmp, u32, struct val_t);
+BPF_HASH(infotmp, u64, struct val_t);
BPF_PERF_OUTPUT(events);
int trace_entry(struct pt_regs *ctx, const char __user *filename)
{
struct val_t val = {};
- u32 pid = bpf_get_current_pid_tgid();
+ u64 id = bpf_get_current_pid_tgid();
+ u32 pid = id >> 32; // PID is higher part
+ u32 tid = id; // Cast and get the lower part
FILTER
if (bpf_get_current_comm(&val.comm, sizeof(val.comm)) == 0) {
- val.pid = bpf_get_current_pid_tgid();
+ val.id = id;
val.ts = bpf_ktime_get_ns();
val.fname = filename;
- infotmp.update(&pid, &val);
+ infotmp.update(&id, &val);
}
return 0;
@@ -83,31 +88,33 @@
int trace_return(struct pt_regs *ctx)
{
- u32 pid = bpf_get_current_pid_tgid();
+ u64 id = bpf_get_current_pid_tgid();
struct val_t *valp;
struct data_t data = {};
u64 tsp = bpf_ktime_get_ns();
- valp = infotmp.lookup(&pid);
+ valp = infotmp.lookup(&id);
if (valp == 0) {
// missed entry
return 0;
}
bpf_probe_read(&data.comm, sizeof(data.comm), valp->comm);
bpf_probe_read(&data.fname, sizeof(data.fname), (void *)valp->fname);
- data.pid = valp->pid;
+ data.id = valp->id;
data.ts = tsp / 1000;
data.ret = PT_REGS_RC(ctx);
events.perf_submit(ctx, &data, sizeof(data));
- infotmp.delete(&pid);
- args_filename.delete(&pid);
+ infotmp.delete(&id);
return 0;
}
"""
-if args.pid:
+if args.tid: # TID trumps PID
+ bpf_text = bpf_text.replace('FILTER',
+ 'if (tid != %s) { return 0; }' % args.tid)
+elif args.pid:
bpf_text = bpf_text.replace('FILTER',
'if (pid != %s) { return 0; }' % args.pid)
else:
@@ -125,7 +132,7 @@
class Data(ct.Structure):
_fields_ = [
- ("pid", ct.c_ulonglong),
+ ("id", ct.c_ulonglong),
("ts", ct.c_ulonglong),
("ret", ct.c_int),
("comm", ct.c_char * TASK_COMM_LEN),
@@ -137,7 +144,8 @@
# header
if args.timestamp:
print("%-14s" % ("TIME(s)"), end="")
-print("%-6s %-16s %4s %3s %s" % ("PID", "COMM", "FD", "ERR", "PATH"))
+print("%-6s %-16s %4s %3s %s" %
+ ("TID" if args.tid else "PID", "COMM", "FD", "ERR", "PATH"))
# process event
def print_event(cpu, data, size):
@@ -165,8 +173,9 @@
delta = event.ts - initial_ts
print("%-14.9f" % (float(delta) / 1000000), end="")
- print("%-6d %-16s %4d %3d %s" % (event.pid, event.comm,
- fd_s, err, event.fname))
+ print("%-6d %-16s %4d %3d %s" %
+ (event.id & 0xffffffff if args.tid else event.id >> 32,
+ event.comm, fd_s, err, event.fname))
# loop with callback to print_event
b["events"].open_perf_buffer(print_event)
