Set io scheduler for mounts (SCSI devs only)

set-io-scheduler.py

#!/usr/bin/python

import glob
import optparse
import os
import time
import stat
import string
import sys


class GetOptions:

    def __init__(self):
        parser = optparse.OptionParser()
        parser.add_option("-s", "--sleep", action="store",
                dest="sleep", type="int",
                help="continously set and sleep")
        parser.add_option("-m", "--mount", action="append",
                dest="mounts",
                help="Mounts to set scheduler for")
        parser.add_option("--scheduler", action="store",
                dest="scheduler", type="string",
                help="Scheduler to set")
        self.parser = parser
        self.parse()

    def parse(self):
        (self.options, self.args) = self.parser.parse_args()

        if not self.mounts:
            print "No mountpoints provided"
            self.print_help_exit()

        if not self.scheduler:
            print "No scheduler provided"
            self.print_help_exit()

        if self.scheduler not in ["cfq", "deadline", "noop", "anticipatory"]:
            print "Invalid scheduler %s" % (self.scheduler)
            self.print_help_exit()

    def __getattr__(self, k):
        return getattr(self.options, k)

    def print_help_exit(self):
        self.parser.print_help()
        exit(1)

def setscheduler(mounts, scheduler="noop"):
    # devices hash device path => "major:minor"
    devices = {}

    paths = glob.glob("/dev/sd*")

    for path in paths:
        if stat.S_ISBLK(os.stat(path).st_mode):
            major = os.major(os.stat(path).st_rdev)
            minor = os.minor(os.stat(path).st_rdev)
            devices[path] = "%d:%d" % (major, minor)

    for mount in mounts:
        if os.path.ismount(mount):
            match = False
            major = os.major(os.stat(mount).st_dev)
            minor = os.minor(os.stat(mount).st_dev)
            for path in devices.keys():
                if devices[path] == "%d:%d" % (major,minor):
                    match = True
                    device = string.strip(os.path.basename(path), string.digits)
                    print "setting %s scheduler for device %s (%s)"\
                            % (scheduler, device, mount)
                    open("/sys/block/%s/queue/scheduler" %(device)\
                            , "w").write("%s\n" % scheduler)
            if not match:
                print "WARNING: No device found for mount %s" % (mount)
        else:
            print "WARNING: %s is not a mountpoint or mounted" % (mount)

def main():
    if os.geteuid() != 0:
        print "Need to be root to run this."
        sys.exit(1)

    opts = GetOptions()
    opts.parse()


    if opts.sleep:
       while True:
            setscheduler(opts.mounts, opts.scheduler)
            print "Sleeping for %d seconds" % (opts.sleep)
            time.sleep(opts.sleep)
    else:
        setscheduler(opts.mounts, opts.scheduler)

if __name__ == "__main__":
    main()