一，工具简介
zfsslower 显示慢于阈值的 ZFS 读取、写入、打开和 fsyncs 操作。
二，代码示例
#!/usr/bin/env python
from __future__ import print_function
from bcc import BPF
import argparse
from time import strftime
# arguments
examples = """examples:
./zfsslower # trace operations slower than 10 ms (default)
./zfsslower 1 # trace operations slower than 1 ms
./zfsslower -j 1 # ... 1 ms, parsable output (csv)
./zfsslower 0 # trace all operations (warning: verbose)
./zfsslower -p 185 # trace PID 185 only
"""
parser = argparse.ArgumentParser(
description="Trace common ZFS file operations slower than a threshold",
formatter_class=argparse.RawDescriptionHelpFormatter,
epilog=examples)
parser.add_argument("-j", "--csv", action="store_true",
help="just print fields: comma-separated values")
parser.add_argu