#!/usr/bin/python
#
# wakeuptime Summarize sleep to wakeup time by waker kernel stack
# For Linux, uses BCC, eBPF.
#
# USAGE: wakeuptime [-h] [-u] [-p PID] [-v] [-f] [duration]
#
# The current implementation uses an unrolled loop for x86_64, and was written
# as a proof of concept. This implementation should be replaced in the future
# with an appropriate bpf_ call, when available.
#
# Currently limited to a stack trace depth of 21 (maxdepth + 1).
#
# Copyright 2016 Netflix, Inc.
# Licensed under the Apache License, Version 2.0 (the "License")
#
# 14-Jan-2016 Brendan Gregg Created this.
from __future__ import print_function
from bcc import BPF
from time import sleep, strftime
import argparse
import signal
# arguments
examples = """examples:
./wakeuptime # trace blocked time with waker stacks
./wakeuptime 5 # trace for 5 seconds only
./wakeuptime -f 5 # 5 seconds, and output in folded format
./wakeuptime -u # don't include kernel threads (user only)
./wakeuptime -p 185 # trace fo PID 185 only
"""
parser = argparse.ArgumentParser(
description="Summarize sleep to wakeup time by waker kernel stack",
formatter_class=argparse.RawDescriptionHelpFormatter,
epilog=examples)
parser.add_argument("-u", "--useronly", action="store_true",
help="user threads only (no kernel threads)")
parser.add_argument("-p", "--pid",
help="trace this PID only")
parser.add_argument("-v", "--verbose", action="store_true",
help="show raw addresses")
parser.add_argument("-f", "--folded", action="store_true",
help="output folded format")
parser.add_argument("duration", nargs="?", default=99999999,
help="duration of trace, in seconds")
args = parser.parse_args()
folded = args.folded
duration = int(args.duration)
debug = 0
maxdepth = 20 # and MAXDEPTH
if args.pid and args.useronly:
print("ERROR: use either -p or -u.")
exit()
# signal handler
def signal_ignore(signal, frame):
print()
# define BPF program
bpf_text = """
#include <uapi/linux/ptrace.h>
#include <linux/sched.h>
#define MAXDEPTH 20
#define MINBLOCK_US 1
struct key_t {
char waker[TASK_COMM_LEN];
char target[TASK_COMM_LEN];
// Skip saving the ip
u64 ret[MAXDEPTH];
};
BPF_HASH(counts, struct key_t);
BPF_HASH(start, u32);
static u64 get_frame(u64 *bp) {
if (*bp) {
// The following stack walker is x86_64/arm64 specific
u64 ret = 0;
if (bpf_probe_read(&ret, sizeof(ret), (void *)(*bp+8)))
return 0;
if (bpf_probe_read(bp, sizeof(*bp), (void *)*bp))
return 0;
#ifdef __x86_64__
if (ret < __START_KERNEL_map)
#elif __aarch64__
if (ret < VA_START)
#else
#error "Unsupported architecture for stack walker"
#endif
return 0;
return ret;
}
return 0;
}
int offcpu(struct pt_regs *ctx) {
u32 pid = bpf_get_current_pid_tgid();
u64 ts = bpf_ktime_get_ns();
// XXX: should filter here too, but need task_struct
start.update(&pid, &ts);
return 0;
}
int waker(struct pt_regs *ctx, struct task_struct *p) {
u32 pid = p->pid;
u64 delta, *tsp, ts;
tsp = start.lookup(&pid);
if (tsp == 0)
return 0; // missed start
start.delete(&pid);
if (FILTER)
return 0;
// calculate delta time
delta = bpf_ktime_get_ns() - *tsp;
delta = delta / 1000;
if (delta < MINBLOCK_US)
return 0;
struct key_t key = {};
u64 zero = 0, *val, bp = 0;
int depth = 0;
bpf_probe_read(&key.target, sizeof(key.target), p->comm);
bpf_get_current_comm(&key.waker, sizeof(key.waker));
bp = PT_REGS_FP(ctx);
// unrolled loop (MAXDEPTH):
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
if (!(key.ret[depth++] = get_frame(&bp))) goto out;
out:
val = counts.lookup_or_init(&key, &zero);
(*val) += delta;
return 0;
}
"""
if args.pid:
filter = 'pid != %s' % args.pid
elif args.useronly:
filter = 'p->flags & PF_KTHREAD'
else:
filter = '0'
bpf_text = bpf_text.replace('FILTER', filter)
if debug:
print(bpf_text)
# initialize BPF
b = BPF(text=bpf_text)
b.attach_kprobe(event="schedule", fn_name="offcpu")
b.attach_kprobe(event="try_to_wake_up", fn_name="waker")
matched = b.num_open_kprobes()
if matched == 0:
print("0 functions traced. Exiting.")
exit()
# header
if not folded:
print("Tracing blocked time (us) by kernel stack", end="")
if duration < 99999999:
print(" for %d secs." % duration)
else:
print("... Hit Ctrl-C to end.")
# output
while (1):
try:
sleep(duration)
except KeyboardInterrupt:
# as cleanup can take many seconds, trap Ctrl-C:
signal.signal(signal.SIGINT, signal_ignore)
if not folded:
print()
counts = b.get_table("counts")
for k, v in sorted(counts.items(), key=lambda counts: counts[1].value):
if folded:
# print folded stack output
line = k.waker.decode('utf-8', 'replace') + ";"
for i in reversed(range(0, maxdepth)):
if k.ret[i] == 0:
continue
line = line + b.ksym(k.ret[i])
if i != 0:
line = line + ";"
print("%s;%s %d" % (line, k.target.decode('utf-8', 'replace'), v.value))
else:
# print default multi-line stack output
print(" %-16s %s" % ("target:", k.target.decode('utf-8', 'replace')))
for i in range(0, maxdepth):
if k.ret[i] == 0:
break
print(" %-16x %s" % (k.ret[i],
b.ksym(k.ret[i])))
print(" %-16s %s" % ("waker:", k.waker.decode('utf-8', 'replace')))
print(" %d\n" % v.value)
counts.clear()
if not folded:
print("Detaching...")
exit()