iotop/ioprio.py

   1 import ctypes
   2 import fnmatch
   3 import os
   4 import time
   5
   6 # From http://git.kernel.org/?p=utils/util-linux-ng/util-linux-ng.git;a=blob;
   7 #      f=configure.ac;h=770eb45ae85d32757fc3cff1d70a7808a627f9f7;hb=HEAD#l363
   8 IOPRIO_GET_ARCH_SYSCALL = [
   9     ('alpha',    443),
  10     ('i*86',     290),
  11     ('ia64*',    1275),
  12     ('powerpc*', 274),
  13     ('s390*',    283),
  14     ('sparc*',   218),
  15     ('sh*',      289),
  16     ('x86_64*',  252),
  17 ]
  18
  19 def find_ioprio_get_syscall_number():
  20     arch = os.uname()[4]
  21
  22     for candidate_arch, syscall_nr in IOPRIO_GET_ARCH_SYSCALL:
  23         if fnmatch.fnmatch(arch, candidate_arch):
  24             return syscall_nr
  25
  26
  27 __NR_ioprio_get = find_ioprio_get_syscall_number()
  28 ctypes_handle = ctypes.CDLL(None)
  29 syscall = ctypes_handle.syscall
  30
  31 PRIORITY_CLASSES = (None, 'rt', 'be', 'idle')
  32
  33 WHO_PROCESS = 1
  34 IOPRIO_CLASS_SHIFT = 13
  35 IOPRIO_PRIO_MASK = (1 << IOPRIO_CLASS_SHIFT) - 1
  36
  37 def ioprio_class(ioprio):
  38     return PRIORITY_CLASSES[ioprio >> IOPRIO_CLASS_SHIFT]
  39
  40 def ioprio_data(ioprio):
  41     return ioprio & IOPRIO_PRIO_MASK
  42
  43 sched_getscheduler = ctypes_handle.sched_getscheduler
  44 SCHED_OTHER, SCHED_FIFO, SCHED_RR, SCHED_BATCH, SCHED_ISO, SCHED_IDLE = range(6)
  45
  46 def get_ioprio_from_sched(pid):
  47     scheduler = sched_getscheduler(pid)
  48     nice = int(open('/proc/%d/stat' % pid).read().split()[18])
  49     ioprio_nice = (nice + 20) / 5
  50
  51     if scheduler in (SCHED_FIFO, SCHED_RR):
  52         return 'rt/%d' % ioprio_nice
  53     elif scheduler == SCHED_IDLE:
  54         return 'idle'
  55     else:
  56         return 'be/%d' % ioprio_nice
  57
  58 def get(pid):
  59     if __NR_ioprio_get is None:
  60         return '?sys'
  61
  62     ioprio = syscall(__NR_ioprio_get, WHO_PROCESS, pid)
  63     if ioprio < 0:
  64         return '?err'
  65
  66     prio_class = ioprio_class(ioprio)
  67     if not prio_class:
  68         return get_ioprio_from_sched(pid)
  69     if prio_class == 'idle':
  70         return prio_class
  71     return '%s/%d' % (prio_class, ioprio_data(ioprio))
  72
  73 def sort_key(key):
  74     if key[0] == '?':
  75         return -ord(key[1])
  76
  77     if '/' in key:
  78         if key.startswith('rt/'):
  79             shift = 0
  80         elif key.startswith('be/'):
  81             shift = 1
  82         prio = int(key.split('/')[1])
  83     elif key == 'idle':
  84         shift = 2
  85         prio = 0
  86
  87     return (1 << (shift * IOPRIO_CLASS_SHIFT)) + prio
  88
  89 if __name__ == '__main__':
  90     import sys
  91     if len(sys.argv) == 2:
  92         pid = int(sys.argv[1])
  93     else:
  94         pid = os.getpid()
  95     print 'pid:', pid
  96     print 'ioprio:', get(pid)
  97