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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 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
  24 # From https://git.kernel.org/?p=utils/util-linux-ng/util-linux-ng.git;a=blob;
  25 #      f=configure.ac;h=770eb45ae85d32757fc3cff1d70a7808a627f9f7;hb=HEAD#l354
  26 # i386 bit userspace under an x86_64 kernel will have its uname() appear as
  27 # 'x86_64' but it will use the i386 syscall number, that's why we consider both
  28 # the architecture name and the word size.
  29 IOPRIO_GET_ARCH_SYSCALL = [
  30     ('alpha',       '*',  443),
  31     ('arm*',        '*',  315),
  32     ('i*86',        '*',  290),
  33     ('ia64*',       '*', 1275),
  34     ('mips*',   '32bit', 4315),
  35     ('mips*',   '64bit', 5274),
  36     ('parisc*',     '*',  268),
  37     ('powerpc*',    '*',  274),
  38     ('s390*',       '*',  283),
  39     ('sparc*',      '*',  218),
  40     ('sh*',         '*',  289),
  41     ('x86_64*', '32bit',  290),
  42     ('x86_64*', '64bit',  252),
  43 ]
  44
  45 IOPRIO_SET_ARCH_SYSCALL = [
  46     ('alpha',       '*',  442),
  47     ('arm*',        '*',  314),
  48     ('i*86',        '*',  289),
  49     ('ia64*',       '*', 1274),
  50     ('mips*',   '32bit', 4314),
  51     ('mips*',   '64bit', 5273),
  52     ('parisc*',     '*',  267),
  53     ('powerpc*',    '*',  273),
  54     ('s390*',       '*',  282),
  55     ('sparc*',      '*',  196),
  56     ('sh*',         '*',  288),
  57     ('x86_64*',  '32bit', 289),
  58     ('x86_64*',  '64bit', 251),
  59 ]
  60
  61
  62 def find_ioprio_syscall_number(syscall_list):
  63     arch = os.uname()[4]
  64     bits = platform.architecture()[0]
  65
  66     for candidate_arch, candidate_bits, syscall_nr in syscall_list:
  67         if fnmatch.fnmatch(arch, candidate_arch) and \
  68            fnmatch.fnmatch(bits, candidate_bits):
  69             return syscall_nr
  70
  71
  72 class IoprioSetError(Exception):
  73     def __init__(self, err):
  74         try:
  75             self.err = os.strerror(err)
  76         except TypeError:
  77             self.err = err
  78
  79 __NR_ioprio_get = find_ioprio_syscall_number(IOPRIO_GET_ARCH_SYSCALL)
  80 __NR_ioprio_set = find_ioprio_syscall_number(IOPRIO_SET_ARCH_SYSCALL)
  81
  82 try:
  83     ctypes_handle = ctypes.CDLL(None, use_errno=True)
  84 except TypeError:
  85     ctypes_handle = ctypes.CDLL(None)
  86
  87 syscall = ctypes_handle.syscall
  88
  89 PRIORITY_CLASSES = [None, 'rt', 'be', 'idle']
  90
  91 IOPRIO_WHO_PROCESS = 1
  92 IOPRIO_CLASS_SHIFT = 13
  93 IOPRIO_PRIO_MASK = (1 << IOPRIO_CLASS_SHIFT) - 1
  94
  95
  96 def ioprio_value(ioprio_class, ioprio_data):
  97     try:
  98         ioprio_class = PRIORITY_CLASSES.index(ioprio_class)
  99     except ValueError:
 100         ioprio_class = PRIORITY_CLASSES.index(None)
 101     return (ioprio_class << IOPRIO_CLASS_SHIFT) | ioprio_data
 102
 103
 104 def ioprio_class(ioprio):
 105     return PRIORITY_CLASSES[ioprio >> IOPRIO_CLASS_SHIFT]
 106
 107
 108 def ioprio_data(ioprio):
 109     return ioprio & IOPRIO_PRIO_MASK
 110
 111 sched_getscheduler = ctypes_handle.sched_getscheduler
 112 SCHED_OTHER, SCHED_FIFO, SCHED_RR, SCHED_BATCH, SCHED_ISO, SCHED_IDLE = \
 113     range(6)
 114
 115 getpriority = ctypes_handle.getpriority
 116 PRIO_PROCESS = 0
 117
 118
 119 def get_ioprio_from_sched(pid):
 120     scheduler = sched_getscheduler(pid)
 121     nice = getpriority(PRIO_PROCESS, pid)
 122     ioprio_nice = (nice + 20) / 5
 123
 124     if scheduler in (SCHED_FIFO, SCHED_RR):
 125         return 'rt/%d' % ioprio_nice
 126     elif scheduler == SCHED_IDLE:
 127         return 'idle'
 128     else:
 129         return 'be/%d' % ioprio_nice
 130
 131
 132 def get(pid):
 133     if __NR_ioprio_get is None:
 134         return '?sys'
 135
 136     ioprio = syscall(__NR_ioprio_get, IOPRIO_WHO_PROCESS, pid)
 137     if ioprio < 0:
 138         return '?err'
 139
 140     prio_class = ioprio_class(ioprio)
 141     if not prio_class:
 142         return get_ioprio_from_sched(pid)
 143     if prio_class == 'idle':
 144         return prio_class
 145     return '%s/%d' % (prio_class, ioprio_data(ioprio))
 146
 147
 148 def set_ioprio(which, who, ioprio_class, ioprio_data):
 149     if __NR_ioprio_set is None:
 150         raise IoprioSetError('No ioprio_set syscall found')
 151
 152     ioprio_val = ioprio_value(ioprio_class, ioprio_data)
 153     ret = syscall(__NR_ioprio_set, which, who, ioprio_val, use_errno=True)
 154     if ret < 0:
 155         try:
 156             err = ctypes.get_errno()
 157         except AttributeError:
 158             err = \
 159                 'Unknown error (errno support not available before Python2.6)'
 160         raise IoprioSetError(err)
 161
 162
 163 def sort_key(key):
 164     if key[0] == '?':
 165         return -ord(key[1])
 166
 167     if '/' in key:
 168         if key.startswith('rt/'):
 169             shift = 0
 170         elif key.startswith('be/'):
 171             shift = 1
 172         prio = int(key.split('/')[1])
 173     elif key == 'idle':
 174         shift = 2
 175         prio = 0
 176
 177     return (1 << (shift * IOPRIO_CLASS_SHIFT)) + prio
 178
 179
 180 def to_class_and_data(ioprio_str):
 181     if '/' in ioprio_str:
 182         split = ioprio_str.split('/')
 183         return (split[0], int(split[1]))
 184     elif ioprio_str == 'idle':
 185         return ('idle', 0)
 186     return (None, None)
 187
 188 if __name__ == '__main__':
 189     import sys
 190     if len(sys.argv) == 2:
 191         pid = int(sys.argv[1])
 192     else:
 193         pid = os.getpid()
 194     print('pid:', pid)
 195     print('ioprio:', get(pid))