一，工具简介

ext4dist跟踪ext4的读取、写入、打开和fsync操作，并将其延迟总结为2的幂次方直方图。

二，代码示例

#!/usr/bin/env pythonfrom __future__ import print_function
from bcc import BPF
from time import sleep, strftime
import argparse# symbols
kallsyms = "/proc/kallsyms"# arguments
examples = """examples:./ext4dist            # show operation latency as a histogram./ext4dist -p 181     # trace PID 181 only./ext4dist 1 10       # print 1 second summaries, 10 times./ext4dist -m 5       # 5s summaries, milliseconds
"""
parser = argparse.ArgumentParser(description="Summarize ext4 operation latency",formatter_class=argparse.RawDescriptionHelpFormatter,epilog=examples)
parser.add_argument("-T", "--notimestamp", action="store_true",help="don't include timestamp on interval output")
parser.add_argument("-m", "--mi