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#!/usr/bin/env 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]
#
# 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 bcc.utils import printb
from time import sleep, strftime
import argparse
import signal
import errno
from sys import stderr
# arg validation
def positive_int(val):
try:
ival = int(val)
except ValueError:
raise argparse.ArgumentTypeError("must be an integer")
if ival < 0:
raise argparse.ArgumentTypeError("must be positive")
return ival
def positive_nonzero_int(val):
ival = positive_int(val)
if ival == 0:
raise argparse.ArgumentTypeError("must be nonzero")
return ival
# 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 for 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",
type=positive_int,
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("--stack-storage-size", default=1024,
type=positive_nonzero_int,
help="the number of unique stack traces that can be stored and "
"displayed (default 1024)")
parser.add_argument("duration", nargs="?", default=99999999,
type=positive_nonzero_int,
help="duration of trace, in seconds")
parser.add_argument("-m", "--min-block-time", default=1,
type=positive_nonzero_int,
help="the amount of time in microseconds over which we " +
"store traces (default 1)")
parser.add_argument("-M", "--max-block-time", default=(1 << 64) - 1,
type=positive_nonzero_int,
help="the amount of time in microseconds under which we " +
"store traces (default U64_MAX)")
parser.add_argument("--ebpf", action="store_true",
help=argparse.SUPPRESS)
args = parser.parse_args()
folded = args.folded
duration = int(args.duration)
debug = 0
if args.pid and args.useronly:
parser.error("use either -p or -u.")
# signal handler
def signal_ignore(signal, frame):
print()
# define BPF program
bpf_text = """
#include <uapi/linux/ptrace.h>
#include <linux/sched.h>
#define MINBLOCK_US MINBLOCK_US_VALUEULL
#define MAXBLOCK_US MAXBLOCK_US_VALUEULL
struct key_t {
int w_k_stack_id;
char waker[TASK_COMM_LEN];
char target[TASK_COMM_LEN];
};
BPF_HASH(counts, struct key_t);
BPF_HASH(start, u32);
BPF_STACK_TRACE(stack_traces, STACK_STORAGE_SIZE);
int offcpu(struct pt_regs *ctx) {
u32 pid = bpf_get_current_pid_tgid();
struct task_struct *p = (struct task_struct *) bpf_get_current_task();
u64 ts;
if (FILTER)
return 0;
ts = bpf_ktime_get_ns();
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) || (delta > MAXBLOCK_US))
return 0;
struct key_t key = {};
key.w_k_stack_id = stack_traces.get_stackid(ctx, BPF_F_REUSE_STACKID);
bpf_probe_read(&key.target, sizeof(key.target), p->comm);
bpf_get_current_comm(&key.waker, sizeof(key.waker));
counts.increment(key, 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)
# set stack storage size
bpf_text = bpf_text.replace('STACK_STORAGE_SIZE', str(args.stack_storage_size))
bpf_text = bpf_text.replace('MINBLOCK_US_VALUE', str(args.min_block_time))
bpf_text = bpf_text.replace('MAXBLOCK_US_VALUE', str(args.max_block_time))
if debug or args.ebpf:
print(bpf_text)
if args.ebpf:
exit()
# 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()
missing_stacks = 0
has_enomem = False
counts = b.get_table("counts")
stack_traces = b.get_table("stack_traces")
for k, v in sorted(counts.items(), key=lambda counts: counts[1].value):
# handle get_stackid errors
# check for an ENOMEM error
if k.w_k_stack_id == -errno.ENOMEM:
missing_stacks += 1
continue
waker_kernel_stack = [] if k.w_k_stack_id < 1 else \
reversed(list(stack_traces.walk(k.w_k_stack_id))[1:])
if folded:
# print folded stack output
line = \
[k.waker] + \
[b.ksym(addr)
for addr in reversed(list(waker_kernel_stack))] + \
[k.target]
printb(b"%s %d" % (b";".join(line), v.value))
else:
# print default multi-line stack output
printb(b" %-16s %s" % (b"target:", k.target))
for addr in waker_kernel_stack:
printb(b" %-16x %s" % (addr, b.ksym(addr)))
printb(b" %-16s %s" % (b"waker:", k.waker))
print(" %d\n" % v.value)
counts.clear()
if missing_stacks > 0:
enomem_str = " Consider increasing --stack-storage-size."
print("WARNING: %d stack traces could not be displayed.%s" %
(missing_stacks, enomem_str),
file=stderr)
if not folded:
print("Detaching...")
exit()