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     ('i*86',        '*',  290),
  33     ('ia64*',       '*', 1275),
  34     ('powerpc*',    '*',  274),
  35     ('s390*',       '*',  283),
  36     ('sparc*',      '*',  218),
  37     ('sh*',         '*',  289),
  38     ('x86_64*', '32bit',  290),
  39     ('x86_64*', '64bit',  252),
  40 ]
  41
  42 IOPRIO_SET_ARCH_SYSCALL = [
  43     ('alpha',       '*',  442),
  44     ('i*86',        '*',  289),
  45     ('ia64*',       '*', 1274),
  46     ('powerpc*',    '*',  273),
  47     ('s390*',       '*',  282),
  48     ('sparc*',      '*',  196),
  49     ('sh*',         '*',  288),
  50     ('x86_64*',  '32bit', 289),
  51     ('x86_64*',  '64bit', 251),
  52 ]
  53
  54 def find_ioprio_syscall_number(syscall_list):
  55     arch = os.uname()[4]
  56     bits = platform.architecture()[0]
  57
  58     for candidate_arch, candidate_bits, syscall_nr in syscall_list:
  59         if fnmatch.fnmatch(arch, candidate_arch) and \
  60            fnmatch.fnmatch(bits, candidate_bits):
  61             return syscall_nr
  62
  63 class IoprioSetError(Exception):
  64     def __init__(self, err):
  65         try:
  66             self.err = os.strerror(err)
  67         except TypeError:
  68             self.err = err
  69
  70 __NR_ioprio_get = find_ioprio_syscall_number(IOPRIO_GET_ARCH_SYSCALL)
  71 __NR_ioprio_set = find_ioprio_syscall_number(IOPRIO_SET_ARCH_SYSCALL)
  72
  73 try:
  74     ctypes_handle = ctypes.CDLL(None, use_errno=True)
  75 except TypeError:
  76     ctypes_handle = ctypes.CDLL(None)
  77
  78 syscall = ctypes_handle.syscall
  79
  80 PRIORITY_CLASSES = [None, 'rt', 'be', 'idle']
  81
  82 IOPRIO_WHO_PROCESS = 1
  83 IOPRIO_CLASS_SHIFT = 13
  84 IOPRIO_PRIO_MASK = (1 << IOPRIO_CLASS_SHIFT) - 1
  85
  86 def ioprio_value(ioprio_class, ioprio_data):
  87     try:
  88         ioprio_class = PRIORITY_CLASSES.index(ioprio_class)
  89     except ValueError:
  90         ioprio_class = PRIORITY_CLASSES.index(None)
  91     return (ioprio_class << IOPRIO_CLASS_SHIFT) | ioprio_data
  92
  93 def ioprio_class(ioprio):
  94     return PRIORITY_CLASSES[ioprio >> IOPRIO_CLASS_SHIFT]
  95
  96 def ioprio_data(ioprio):
  97     return ioprio & IOPRIO_PRIO_MASK
  98
  99 sched_getscheduler = ctypes_handle.sched_getscheduler
 100 SCHED_OTHER, SCHED_FIFO, SCHED_RR, SCHED_BATCH, SCHED_ISO, SCHED_IDLE = range(6)
 101
 102 getpriority = ctypes_handle.getpriority
 103 PRIO_PROCESS = 0
 104
 105 def get_ioprio_from_sched(pid):
 106     scheduler = sched_getscheduler(pid)
 107     nice = getpriority(PRIO_PROCESS, pid)
 108     ioprio_nice = (nice + 20) / 5
 109
 110     if scheduler in (SCHED_FIFO, SCHED_RR):
 111         return 'rt/%d' % ioprio_nice
 112     elif scheduler == SCHED_IDLE:
 113         return 'idle'
 114     else:
 115         return 'be/%d' % ioprio_nice
 116
 117 def get(pid):
 118     if __NR_ioprio_get is None:
 119         return '?sys'
 120
 121     ioprio = syscall(__NR_ioprio_get, IOPRIO_WHO_PROCESS, pid)
 122     if ioprio < 0:
 123         return '?err'
 124
 125     prio_class = ioprio_class(ioprio)
 126     if not prio_class:
 127         return get_ioprio_from_sched(pid)
 128     if prio_class == 'idle':
 129         return prio_class
 130     return '%s/%d' % (prio_class, ioprio_data(ioprio))
 131
 132 def set_ioprio(which, who, ioprio_class, ioprio_data):
 133     if __NR_ioprio_set is None:
 134         raise IoprioSetError('No ioprio_set syscall found')
 135
 136     ioprio_val = ioprio_value(ioprio_class, ioprio_data)
 137     ret = syscall(__NR_ioprio_set, which, who, ioprio_val, use_errno=True)
 138     if ret < 0:
 139         try:
 140             err = ctypes.get_errno()
 141         except AttributeError:
 142             err = 'Unknown error (errno support not available before Python2.6)'
 143         raise IoprioSetError(err)
 144
 145 def sort_key(key):
 146     if key[0] == '?':
 147         return -ord(key[1])
 148
 149     if '/' in key:
 150         if key.startswith('rt/'):
 151             shift = 0
 152         elif key.startswith('be/'):
 153             shift = 1
 154         prio = int(key.split('/')[1])
 155     elif key == 'idle':
 156         shift = 2
 157         prio = 0
 158
 159     return (1 << (shift * IOPRIO_CLASS_SHIFT)) + prio
 160
 161 def to_class_and_data(ioprio_str):
 162     if '/' in ioprio_str:
 163         split = ioprio_str.split('/')
 164         return (split[0], int(split[1]))
 165     elif ioprio_str == 'idle':
 166         return ('idle', 0)
 167     return (None, None)
 168
 169 if __name__ == '__main__':
 170     import sys
 171     if len(sys.argv) == 2:
 172         pid = int(sys.argv[1])
 173     else:
 174         pid = os.getpid()
 175     print 'pid:', pid
 176     print 'ioprio:', get(pid)
 177