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
  24 # From http://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     ('parisc*',     '*',  268),
  35     ('powerpc*',    '*',  274),
  36     ('s390*',       '*',  283),
  37     ('sparc*',      '*',  218),
  38     ('sh*',         '*',  289),
  39     ('x86_64*', '32bit',  290),
  40     ('x86_64*', '64bit',  252),
  41 ]
  42
  43 IOPRIO_SET_ARCH_SYSCALL = [
  44     ('alpha',       '*',  442),
  45     ('arm*',        '*',  314),
  46     ('i*86',        '*',  289),
  47     ('ia64*',       '*', 1274),
  48     ('parisc*',     '*',  267),
  49     ('powerpc*',    '*',  273),
  50     ('s390*',       '*',  282),
  51     ('sparc*',      '*',  196),
  52     ('sh*',         '*',  288),
  53     ('x86_64*',  '32bit', 289),
  54     ('x86_64*',  '64bit', 251),
  55 ]
  56
  57 def find_ioprio_syscall_number(syscall_list):
  58     arch = os.uname()[4]
  59     bits = platform.architecture()[0]
  60
  61     for candidate_arch, candidate_bits, syscall_nr in syscall_list:
  62         if fnmatch.fnmatch(arch, candidate_arch) and \
  63            fnmatch.fnmatch(bits, candidate_bits):
  64             return syscall_nr
  65
  66 class IoprioSetError(Exception):
  67     def __init__(self, err):
  68         try:
  69             self.err = os.strerror(err)
  70         except TypeError:
  71             self.err = err
  72
  73 __NR_ioprio_get = find_ioprio_syscall_number(IOPRIO_GET_ARCH_SYSCALL)
  74 __NR_ioprio_set = find_ioprio_syscall_number(IOPRIO_SET_ARCH_SYSCALL)
  75
  76 try:
  77     ctypes_handle = ctypes.CDLL(None, use_errno=True)
  78 except TypeError:
  79     ctypes_handle = ctypes.CDLL(None)
  80
  81 syscall = ctypes_handle.syscall
  82
  83 PRIORITY_CLASSES = [None, 'rt', 'be', 'idle']
  84
  85 IOPRIO_WHO_PROCESS = 1
  86 IOPRIO_CLASS_SHIFT = 13
  87 IOPRIO_PRIO_MASK = (1 << IOPRIO_CLASS_SHIFT) - 1
  88
  89 def ioprio_value(ioprio_class, ioprio_data):
  90     try:
  91         ioprio_class = PRIORITY_CLASSES.index(ioprio_class)
  92     except ValueError:
  93         ioprio_class = PRIORITY_CLASSES.index(None)
  94     return (ioprio_class << IOPRIO_CLASS_SHIFT) | ioprio_data
  95
  96 def ioprio_class(ioprio):
  97     return PRIORITY_CLASSES[ioprio >> IOPRIO_CLASS_SHIFT]
  98
  99 def ioprio_data(ioprio):
 100     return ioprio & IOPRIO_PRIO_MASK
 101
 102 sched_getscheduler = ctypes_handle.sched_getscheduler
 103 SCHED_OTHER, SCHED_FIFO, SCHED_RR, SCHED_BATCH, SCHED_ISO, SCHED_IDLE = range(6)
 104
 105 getpriority = ctypes_handle.getpriority
 106 PRIO_PROCESS = 0
 107
 108 def get_ioprio_from_sched(pid):
 109     scheduler = sched_getscheduler(pid)
 110     nice = getpriority(PRIO_PROCESS, pid)
 111     ioprio_nice = (nice + 20) / 5
 112
 113     if scheduler in (SCHED_FIFO, SCHED_RR):
 114         return 'rt/%d' % ioprio_nice
 115     elif scheduler == SCHED_IDLE:
 116         return 'idle'
 117     else:
 118         return 'be/%d' % ioprio_nice
 119
 120 def get(pid):
 121     if __NR_ioprio_get is None:
 122         return '?sys'
 123
 124     ioprio = syscall(__NR_ioprio_get, IOPRIO_WHO_PROCESS, pid)
 125     if ioprio < 0:
 126         return '?err'
 127
 128     prio_class = ioprio_class(ioprio)
 129     if not prio_class:
 130         return get_ioprio_from_sched(pid)
 131     if prio_class == 'idle':
 132         return prio_class
 133     return '%s/%d' % (prio_class, ioprio_data(ioprio))
 134
 135 def set_ioprio(which, who, ioprio_class, ioprio_data):
 136     if __NR_ioprio_set is None:
 137         raise IoprioSetError('No ioprio_set syscall found')
 138
 139     ioprio_val = ioprio_value(ioprio_class, ioprio_data)
 140     ret = syscall(__NR_ioprio_set, which, who, ioprio_val, use_errno=True)
 141     if ret < 0:
 142         try:
 143             err = ctypes.get_errno()
 144         except AttributeError:
 145             err = 'Unknown error (errno support not available before Python2.6)'
 146         raise IoprioSetError(err)
 147
 148 def sort_key(key):
 149     if key[0] == '?':
 150         return -ord(key[1])
 151
 152     if '/' in key:
 153         if key.startswith('rt/'):
 154             shift = 0
 155         elif key.startswith('be/'):
 156             shift = 1
 157         prio = int(key.split('/')[1])
 158     elif key == 'idle':
 159         shift = 2
 160         prio = 0
 161
 162     return (1 << (shift * IOPRIO_CLASS_SHIFT)) + prio
 163
 164 def to_class_and_data(ioprio_str):
 165     if '/' in ioprio_str:
 166         split = ioprio_str.split('/')
 167         return (split[0], int(split[1]))
 168     elif ioprio_str == 'idle':
 169         return ('idle', 0)
 170     return (None, None)
 171
 172 if __name__ == '__main__':
 173     import sys
 174     if len(sys.argv) == 2:
 175         pid = int(sys.argv[1])
 176     else:
 177         pid = os.getpid()
 178     print('pid:', pid)
 179     print('ioprio:', get(pid))
 180