一，工具简介
xfsdist 追踪 XFS 的读取、写入、打开和 fsyncs 操作，并将其延迟以 2 的幂次直方图的形式进行总结。例如：
二，代码示例
#!/usr/bin/env python
from __future__ import print_function
from bcc import BPF
from time import sleep, strftime
import argparse
# arguments
examples = """examples:
./xfsdist # show operation latency as a histogram
./xfsdist -p 181 # trace PID 181 only
./xfsdist 1 10 # print 1 second summaries, 10 times
./xfsdist -m 5 # 5s summaries, milliseconds
"""
parser = argparse.ArgumentParser(
description="Summarize XFS 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", "--milliseconds", action="sto
