iodelay.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import argparse
import logging
import os
import signal
import threading


def parse_opts():
    parser = argparse.ArgumentParser(prog='iodelay')
    parser.add_argument('--dev', help='dev' )
    parser.add_argument('--base', type = int, help='delay')
    parser.add_argument('--step', type = int, help='step')
    parser.add_argument('--cycle', type = int, help='cycle')
    parser.add_argument('--type', choices='rw', help='rdelay or wdelay')

    subparsers = parser.add_subparsers(help='sub-command help')
    parser_inc = subparsers.add_parser('inc', help='inc iodelay')
    parser_inc.set_defaults(func=inc)
    parser_dec = subparsers.add_parser('dec', help='dec iodelay')
    parser_dec.set_defaults(func=dec)

    return parser.parse_args()

rsrc = '''global inject
probe procfs("rinject").write {
    inject = $value;
}
probe vfs.read.return {
    if (inject == "off\\n") {
        exit();
    }
    if ($return && devname == @1) {
        udelay($2);
    }
}
'''

wsrc = '''global inject
probe procfs("winject").write {
    inject = $value;
}
probe vfs.write.return {
    if (inject == "off\\n") {
        exit();
    }
    if ($return && devname == @1) {
        udelay($2);
    }
}
'''

with open('ridd.stp', 'w') as f:
    f.write(rsrc)

with open('widd.stp', 'w') as f:
    f.write(wsrc)

item = 'widd'
wctl = "/proc/systemtap/widd/winject"
rctr = "/proc/systemtap/ridd/rinject"

def inc(args):
    global item
    global wctl
    global rctl

    ctr = wctr
    if args.type == 'r':
        item = "ridd"
        ctl = rctl
    run(args.cycle, item, args.dev, args.base, args.step, ctl)

def dec(args):
    global item
    global wctl
    global rctl

    ctl = wctl
    if args.type == 'r':
        item = "ridd"
        ctl = rctr
    run(args.cycle, item, args.dev, args.base, -args.step, ctl)

def run(cycle, item, dev, delay, step, ctl):
    os.system('echo off|sudo tee %s' % ctl)

    cmd1 = 'sudo stap -p4 -DMAXSKIPPED=9999 -m %s -g %s %s %s' % (item, '%s.stp' % item, dev, delay)
    logging.info(cmd1)
    ret = os.system(cmd1) != 0
    if ret != 0:
        logging.fatal(cmd1)
        exit(1)


    cmd2 = 'sudo staprun %s.ko &' % item
    logging.info(cmd2)
    ret = os.system(cmd2) != 0
    if ret != 0:
        logging.fatal(cmd2)
        exit(1)

    delay += step
    if delay < 0:
        delay = 0
    t = threading.Timer(cycle, run, (cycle, item, dev, delay, step, ctl))
    t.start()

if __name__ == "__main__":
    logging.basicConfig(level=logging.INFO)
    args = parse_opts()
    args.func(args)

eg:

./iodelay.py --dev sda3 --base 10 --step 1 --cycle 1 --type=w dec
./iodelay.py --dev sda3 --base 10 --step 1 --cycle 1 --type=r inc

参数说明：

1. dev是分区名称；
2. base是初始延迟;
3. step是延迟变化步长；
4. cycle是变化周期，单位是s；
5. type只有两个选择，w代表写延迟，r代表读延迟；
6. dec是周期性减少，inc是周期性增。