iotop/ioprio.py

   1 # This program is free software; you can redistribute it and/or modify
   2 # it under the terms of the GNU General Public License as published by
   3 # the Free Software Foundation; either version 2 of the License, or
   4 # (at your option) any later version.
   5 #
   6 # This program is distributed in the hope that it will be useful,
   7 # but WITHOUT ANY WARRANTY; without even the implied warranty of
   8 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   9 # GNU Library General Public License for more details.
  10 #
  11 # You should have received a copy of the GNU General Public License
  12 # along with this program; if not, write to the Free Software
  13 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  14 #
  15 # See the COPYING file for license information.
  16 #
  17 # Copyright (c) 2007 Guillaume Chazarain <guichaz@gmail.com>
  18
  19 import ctypes
  20 import fnmatch
  21 import os
  22 import platform
  23 import time
  24
  25 # From http://git.kernel.org/?p=utils/util-linux-ng/util-linux-ng.git;a=blob;
  26 #      f=configure.ac;h=770eb45ae85d32757fc3cff1d70a7808a627f9f7;hb=HEAD#l354
  27 # i386 bit userspace under an x86_64 kernel will have its uname() appear as
  28 # 'x86_64' but it will use the i386 syscall number, that's why we consider both
  29 # the architecture name and the word size.
  30 IOPRIO_GET_ARCH_SYSCALL = [
  31     ('alpha',       '*',  443),
  32     ('arm*',        '*',  315),
  33     ('i*86',        '*',  290),
  34     ('ia64*',       '*', 1275),
  35     ('parisc*',     '*',  268),
  36     ('powerpc*',    '*',  274),
  37     ('s390*',       '*',  283),
  38     ('sparc*',      '*',  218),
  39     ('sh*',         '*',  289),
  40     ('x86_64*', '32bit',  290),
  41     ('x86_64*', '64bit',  252),
  42 ]
  43
  44 IOPRIO_SET_ARCH_SYSCALL = [
  45     ('alpha',       '*',  442),
  46     ('arm*',        '*',  314),
  47     ('i*86',        '*',  289),
  48     ('ia64*',       '*', 1274),
  49     ('parisc*',     '*',  267),
  50     ('powerpc*',    '*',  273),
  51     ('s390*',       '*',  282),
  52     ('sparc*',      '*',  196),
  53     ('sh*',         '*',  288),
  54     ('x86_64*',  '32bit', 289),
  55     ('x86_64*',  '64bit', 251),
  56 ]
  57
  58 def find_ioprio_syscall_number(syscall_list):
  59     arch = os.uname()[4]
  60     bits = platform.architecture()[0]
  61
  62     for candidate_arch, candidate_bits, syscall_nr in syscall_list:
  63         if fnmatch.fnmatch(arch, candidate_arch) and \
  64            fnmatch.fnmatch(bits, candidate_bits):
  65             return syscall_nr
  66
  67 class IoprioSetError(Exception):
  68     def __init__(self, err):
  69         try:
  70             self.err = os.strerror(err)
  71         except TypeError:
  72             self.err = err
  73
  74 __NR_ioprio_get = find_ioprio_syscall_number(IOPRIO_GET_ARCH_SYSCALL)
  75 __NR_ioprio_set = find_ioprio_syscall_number(IOPRIO_SET_ARCH_SYSCALL)
  76
  77 try:
  78     ctypes_handle = ctypes.CDLL(None, use_errno=True)
  79 except TypeError:
  80     ctypes_handle = ctypes.CDLL(None)
  81
  82 syscall = ctypes_handle.syscall
  83
  84 PRIORITY_CLASSES = [None, 'rt', 'be', 'idle']
  85
  86 IOPRIO_WHO_PROCESS = 1
  87 IOPRIO_CLASS_SHIFT = 13
  88 IOPRIO_PRIO_MASK = (1 << IOPRIO_CLASS_SHIFT) - 1
  89
  90 def ioprio_value(ioprio_class, ioprio_data):
  91     try:
  92         ioprio_class = PRIORITY_CLASSES.index(ioprio_class)
  93     except ValueError:
  94         ioprio_class = PRIORITY_CLASSES.index(None)
  95     return (ioprio_class << IOPRIO_CLASS_SHIFT) | ioprio_data
  96
  97 def ioprio_class(ioprio):
  98     return PRIORITY_CLASSES[ioprio >> IOPRIO_CLASS_SHIFT]
  99
 100 def ioprio_data(ioprio):
 101     return ioprio & IOPRIO_PRIO_MASK
 102
 103 sched_getscheduler = ctypes_handle.sched_getscheduler
 104 SCHED_OTHER, SCHED_FIFO, SCHED_RR, SCHED_BATCH, SCHED_ISO, SCHED_IDLE = range(6)
 105
 106 getpriority = ctypes_handle.getpriority
 107 PRIO_PROCESS = 0
 108
 109 def get_ioprio_from_sched(pid):
 110     scheduler = sched_getscheduler(pid)
 111     nice = getpriority(PRIO_PROCESS, pid)
 112     ioprio_nice = (nice + 20) / 5
 113
 114     if scheduler in (SCHED_FIFO, SCHED_RR):
 115         return 'rt/%d' % ioprio_nice
 116     elif scheduler == SCHED_IDLE:
 117         return 'idle'
 118     else:
 119         return 'be/%d' % ioprio_nice
 120
 121 def get(pid):
 122     if __NR_ioprio_get is None:
 123         return '?sys'
 124
 125     ioprio = syscall(__NR_ioprio_get, IOPRIO_WHO_PROCESS, pid)
 126     if ioprio < 0:
 127         return '?err'
 128
 129     prio_class = ioprio_class(ioprio)
 130     if not prio_class:
 131         return get_ioprio_from_sched(pid)
 132     if prio_class == 'idle':
 133         return prio_class
 134     return '%s/%d' % (prio_class, ioprio_data(ioprio))
 135
 136 def set_ioprio(which, who, ioprio_class, ioprio_data):
 137     if __NR_ioprio_set is None:
 138         raise IoprioSetError('No ioprio_set syscall found')
 139
 140     ioprio_val = ioprio_value(ioprio_class, ioprio_data)
 141     ret = syscall(__NR_ioprio_set, which, who, ioprio_val, use_errno=True)
 142     if ret < 0:
 143         try:
 144             err = ctypes.get_errno()
 145         except AttributeError:
 146             err = 'Unknown error (errno support not available before Python2.6)'
 147         raise IoprioSetError(err)
 148
 149 def sort_key(key):
 150     if key[0] == '?':
 151         return -ord(key[1])
 152
 153     if '/' in key:
 154         if key.startswith('rt/'):
 155             shift = 0
 156         elif key.startswith('be/'):
 157             shift = 1
 158         prio = int(key.split('/')[1])
 159     elif key == 'idle':
 160         shift = 2
 161         prio = 0
 162
 163     return (1 << (shift * IOPRIO_CLASS_SHIFT)) + prio
 164
 165 def to_class_and_data(ioprio_str):
 166     if '/' in ioprio_str:
 167         split = ioprio_str.split('/')
 168         return (split[0], int(split[1]))
 169     elif ioprio_str == 'idle':
 170         return ('idle', 0)
 171     return (None, None)
 172
 173 if __name__ == '__main__':
 174     import sys
 175     if len(sys.argv) == 2:
 176         pid = int(sys.argv[1])
 177     else:
 178         pid = os.getpid()
 179     print 'pid:', pid
 180     print 'ioprio:', get(pid)
 181