Mini Shell

# code for cores isolation was inspired by Tuna implementation
# perf code was borrowed from kernel/tools/perf/python/twatch.py
# thanks to Arnaldo Carvalho de Melo <acme@redhat.com>

from . import base
from .decorators import *
import tuned.logs
import re
from subprocess import *
import threading
import perf
import select
import tuned.consts as consts
import procfs
import schedutils
from tuned.utils.commands import commands
import errno

log = tuned.logs.get()

class SchedulerParams(object):
	def __init__(self, cmd, cmdline = None, scheduler = None,
			priority = None, affinity = None):
		self._cmd = cmd
		self.cmdline = cmdline
		self.scheduler = scheduler
		self.priority = priority
		self.affinity = affinity

	@property
	def affinity(self):
		if self._affinity is None:
			return None
		else:
			return self._cmd.bitmask2cpulist(self._affinity)

	@affinity.setter
	def affinity(self, value):
		if value is None:
			self._affinity = None
		else:
			self._affinity = self._cmd.cpulist2bitmask(value)

class IRQAffinities(object):
	def __init__(self):
		self.irqs = {}
		self.default = None

class SchedulerPlugin(base.Plugin):
	"""
	Plugin for tuning of scheduler. Currently it can control scheduling
	priorities of system threads (it is substitution for the rtctl tool).
	"""

	_dict_schedcfg2num = {
			"f": schedutils.SCHED_FIFO,
			"b": schedutils.SCHED_BATCH,
			"r": schedutils.SCHED_RR,
			"o": schedutils.SCHED_OTHER,
			"i": schedutils.SCHED_IDLE,
			}

	def __init__(self, monitor_repository, storage_factory, hardware_inventory, device_matcher, device_matcher_udev, plugin_instance_factory, global_cfg, variables):
		super(SchedulerPlugin, self).__init__(monitor_repository, storage_factory, hardware_inventory, device_matcher, device_matcher_udev, plugin_instance_factory, global_cfg, variables)
		self._has_dynamic_options = True
		self._daemon = consts.CFG_DEF_DAEMON
		self._sleep_interval = int(consts.CFG_DEF_SLEEP_INTERVAL)
		if global_cfg is not None:
			self._daemon = global_cfg.get_bool(consts.CFG_DAEMON, consts.CFG_DEF_DAEMON)
			self._sleep_interval = int(global_cfg.get(consts.CFG_SLEEP_INTERVAL, consts.CFG_DEF_SLEEP_INTERVAL))
		self._cmd = commands()
		# default is to whitelist all and blacklist none
		self._ps_whitelist = ".*"
		self._ps_blacklist = ""
		self._cpus = perf.cpu_map()
		self._scheduler_storage_key = self._storage_key(
				command_name = "scheduler")
		self._irq_storage_key = self._storage_key(
				command_name = "irq")

	def _instance_init(self, instance):
		instance._has_dynamic_tuning = False
		instance._has_static_tuning = True
		# this is hack, runtime_tuning should be covered by dynamic_tuning configuration
		# TODO: add per plugin dynamic tuning configuration and use dynamic_tuning configuration
		# instead of runtime_tuning
		instance._runtime_tuning = True

		# FIXME: do we want to do this here?
		# recover original values in case of crash
		self._scheduler_original = self._storage.get(
				self._scheduler_storage_key, {})
		if len(self._scheduler_original) > 0:
			log.info("recovering scheduling settings from previous run")
			self._restore_ps_affinity()
			self._scheduler_original = {}
			self._storage.unset(self._scheduler_storage_key)

		instance._scheduler = instance.options
		for k in instance._scheduler:
			instance._scheduler[k] = self._variables.expand(instance._scheduler[k])
		if self._cmd.get_bool(instance._scheduler.get("runtime", 1)) == "0":
			instance._runtime_tuning = False
		instance._terminate = threading.Event()
		if self._daemon and instance._runtime_tuning:
			try:
				instance._threads = perf.thread_map()
				evsel = perf.evsel(type = perf.TYPE_SOFTWARE,
					config = perf.COUNT_SW_DUMMY,
					task = 1, comm = 1, mmap = 0, freq = 0,
					wakeup_events = 1, watermark = 1,
					sample_type = perf.SAMPLE_TID | perf.SAMPLE_CPU)
				evsel.open(cpus = self._cpus, threads = instance._threads)
				instance._evlist = perf.evlist(self._cpus, instance._threads)
				instance._evlist.add(evsel)
				instance._evlist.mmap()
			# no perf
			except:
				instance._runtime_tuning = False

	def _instance_cleanup(self, instance):
		pass

	@classmethod
	def _get_config_options(cls):
		return {
			"isolated_cores":       None,
			"ps_whitelist": None,
			"ps_blacklist": None,
		}

	# Raises OSError, IOError
	def _get_cmdline(self, process):
		if not isinstance(process, procfs.process):
			pid = process
			process = procfs.process(pid)
		cmdline = procfs.process_cmdline(process)
		if self._is_kthread(process):
			cmdline = "[" + cmdline + "]"
		return cmdline

	# Raises OSError, IOError
	def get_processes(self):
		ps = procfs.pidstats()
		ps.reload_threads()
		processes = {}
		for proc in ps.values():
			try:
				cmd = self._get_cmdline(proc)
				pid = proc["pid"]
				processes[pid] = cmd
				if "threads" in proc:
					for pid in proc["threads"].keys():
						cmd = self._get_cmdline(proc)
						processes[pid] = cmd
			except (OSError, IOError) as e:
				if e.errno == errno.ENOENT \
						or e.errno == errno.ESRCH:
					continue
				else:
					raise
		return processes

	# Raises OSError
	# Raises SystemError with old (pre-0.4) python-schedutils
	# instead of OSError
	# If PID doesn't exist, errno == ESRCH
	def _get_rt(self, pid):
		scheduler = schedutils.get_scheduler(pid)
		sched_str = schedutils.schedstr(scheduler)
		priority = schedutils.get_priority(pid)
		log.debug("Read scheduler policy '%s' and priority '%d' of PID '%d'"
				% (sched_str, priority, pid))
		return (scheduler, priority)

	def _set_rt(self, pid, sched, prio):
		sched_str = schedutils.schedstr(sched)
		log.debug("Setting scheduler policy to '%s' and priority to '%d' of PID '%d'."
				% (sched_str, prio, pid))
		try:
			prio_min = schedutils.get_priority_min(sched)
			prio_max = schedutils.get_priority_max(sched)
			if prio < prio_min or prio > prio_max:
				log.error("Priority for %s must be in range %d - %d. '%d' was given."
						% (sched_str, prio_min,
						prio_max, prio))
		# Workaround for old (pre-0.4) python-schedutils which raised
		# SystemError instead of OSError
		except (SystemError, OSError) as e:
			log.error("Failed to get allowed priority range: %s"
					% e)
		try:
			schedutils.set_scheduler(pid, sched, prio)
		except (SystemError, OSError) as e:
			if hasattr(e, "errno") and e.errno == errno.ESRCH:
				log.debug("Failed to set scheduling parameters of PID %d, the task vanished."
						% pid)
			else:
				log.error("Failed to set scheduling parameters of PID %d: %s"
						% (pid, e))

	# process is a procfs.process object
	# Raises OSError, IOError
	def _is_kthread(self, process):
		return process["stat"]["flags"] & procfs.pidstat.PF_KTHREAD != 0

	# Return codes:
	# 0 - Affinity is fixed
	# 1 - Affinity is changeable
	# -1 - Task vanished
	# -2 - Error
	def _affinity_changeable(self, pid):
		try:
			process = procfs.process(pid)
			if process["stat"].is_bound_to_cpu():
				if process["stat"]["state"] == "Z":
					log.debug("Affinity of zombie task with PID %d cannot be changed, the task's affinity mask is fixed."
							% pid)
				elif self._is_kthread(process):
					log.debug("Affinity of kernel thread with PID %d cannot be changed, the task's affinity mask is fixed."
							% pid)
				else:
					log.warn("Affinity of task with PID %d cannot be changed, the task's affinity mask is fixed."
							% pid)
				return 0
			else:
				return 1
		except (OSError, IOError) as e:
			if e.errno == errno.ENOENT or e.errno == errno.ESRCH:
				log.debug("Failed to get task info for PID %d, the task vanished."
						% pid)
				return -1
			else:
				log.error("Failed to get task info for PID %d: %s"
						% (pid, e))
				return -2
		except (AttributeError, KeyError) as e:
			log.error("Failed to get task info for PID %d: %s"
					% (pid, e))
			return -2

	def _store_orig_process_rt(self, pid, scheduler, priority):
		try:
			params = self._scheduler_original[pid]
		except KeyError:
			params = SchedulerParams(self._cmd)
			self._scheduler_original[pid] = params
		if params.scheduler is None and params.priority is None:
			params.scheduler = scheduler
			params.priority = priority

	def _tune_process_rt(self, pid, sched, prio):
		cont = True
		if sched is None and prio is None:
			return cont
		try:
			(prev_sched, prev_prio) = self._get_rt(pid)
			if sched is None:
				sched = prev_sched
			self._set_rt(pid, sched, prio)
			self._store_orig_process_rt(pid, prev_sched, prev_prio)
		except (SystemError, OSError) as e:
			if hasattr(e, "errno") and e.errno == errno.ESRCH:
				log.debug("Failed to read scheduler policy of PID %d, the task vanished."
						% pid)
				if pid in self._scheduler_original:
					del self._scheduler_original[pid]
				cont = False
			else:
				log.error("Refusing to set scheduler and priority of PID %d, reading original scheduling parameters failed: %s"
						% (pid, e))
		return cont

	def _store_orig_process_affinity(self, pid, affinity):
		try:
			params = self._scheduler_original[pid]
		except KeyError:
			params = SchedulerParams(self._cmd)
			self._scheduler_original[pid] = params
		if params.affinity is None:
			params.affinity = affinity

	def _tune_process_affinity(self, pid, affinity, intersect = False):
		cont = True
		if affinity is None:
			return cont
		try:
			prev_affinity = self._get_affinity(pid)
			if intersect:
				affinity = self._get_intersect_affinity(
						prev_affinity, affinity,
						affinity)
			self._set_affinity(pid, affinity)
			self._store_orig_process_affinity(pid,
					prev_affinity)
		except (SystemError, OSError) as e:
			if hasattr(e, "errno") and e.errno == errno.ESRCH:
				log.debug("Failed to read affinity of PID %d, the task vanished."
						% pid)
				if pid in self._scheduler_original:
					del self._scheduler_original[pid]
				cont = False
			else:
				log.error("Refusing to set CPU affinity of PID %d, reading original affinity failed: %s"
						% (pid, e))
		return cont

	#tune process and store previous values
	def _tune_process(self, pid, cmd, sched, prio, affinity):
		cont = self._tune_process_rt(pid, sched, prio)
		if not cont:
			return
		cont = self._tune_process_affinity(pid, affinity)
		if not cont or pid not in self._scheduler_original:
			return
		self._scheduler_original[pid].cmdline = cmd

	def _convert_sched_params(self, str_scheduler, str_priority):
		scheduler = self._dict_schedcfg2num.get(str_scheduler)
		if scheduler is None and str_scheduler != "*":
			log.error("Invalid scheduler: %s. Scheduler and priority will be ignored."
					% str_scheduler)
			return (None, None)
		else:
			try:
				priority = int(str_priority)
			except ValueError:
				log.error("Invalid priority: %s. Scheduler and priority will be ignored."
							% str_priority)
				return (None, None)
		return (scheduler, priority)

	def _convert_affinity(self, str_affinity):
		if str_affinity == "*":
			affinity = None
		else:
			affinity = self._cmd.hex2cpulist(str_affinity)
			if not affinity:
				log.error("Invalid affinity: %s. It will be ignored."
						% str_affinity)
				affinity = None
		return affinity

	def _convert_sched_cfg(self, vals):
		(rule_prio, scheduler, priority, affinity, regex) = vals
		(scheduler, priority) = self._convert_sched_params(
				scheduler, priority)
		affinity = self._convert_affinity(affinity)
		return (rule_prio, scheduler, priority, affinity, regex)

	def _instance_apply_static(self, instance):
		super(SchedulerPlugin, self)._instance_apply_static(instance)
		try:
			ps = self.get_processes()
		except (OSError, IOError) as e:
			log.error("error applying tuning, cannot get information about running processes: %s"
					% e)
			return
		sched_cfg = [(option, str(value).split(":", 4)) for option, value in instance._scheduler.items()]
		buf = [(option, self._convert_sched_cfg(vals))
				for option, vals in sched_cfg
				if re.match(r"group\.", option)
				and len(vals) == 5]
		sched_cfg = sorted(buf, key=lambda option_vals: option_vals[1][0])
		sched_all = dict()
		# for runtime tunning
		instance._sched_lookup = {}
		for option, (rule_prio, scheduler, priority, affinity, regex) \
				in sched_cfg:
			try:
				r = re.compile(regex)
			except re.error as e:
				log.error("error compiling regular expression: '%s'" % str(regex))
				continue
			processes = [(pid, cmd) for pid, cmd in ps.items() if re.search(r, cmd) is not None]
			#cmd - process name, option - group name
			sched = dict([(pid, (cmd, option, scheduler, priority, affinity, regex))
					for pid, cmd in processes])
			sched_all.update(sched)
			regex = str(regex).replace("(", r"\(")
			regex = regex.replace(")", r"\)")
			instance._sched_lookup[regex] = [scheduler, priority, affinity]
		for pid, (cmd, option, scheduler, priority, affinity, regex) \
				in sched_all.items():
			self._tune_process(pid, cmd, scheduler,
					priority, affinity)
		self._storage.set(self._scheduler_storage_key,
				self._scheduler_original)
		if self._daemon and instance._runtime_tuning:
			instance._thread = threading.Thread(target = self._thread_code, args = [instance])
			instance._thread.start()

	def _restore_ps_affinity(self):
		try:
			ps = self.get_processes()
		except (OSError, IOError) as e:
			log.error("error unapplying tuning, cannot get information about running processes: %s"
					% e)
			return
		for pid, orig_params in self._scheduler_original.items():
			# if command line for the pid didn't change, it's very probably the same process
			if pid not in ps or ps[pid] != orig_params.cmdline:
				continue
			if orig_params.scheduler is not None \
					and orig_params.priority is not None:
				self._set_rt(pid, orig_params.scheduler,
						orig_params.priority)
			if orig_params.affinity is not None:
				self._set_affinity(pid, orig_params.affinity)
		self._scheduler_original = {}
		self._storage.unset(self._scheduler_storage_key)

	def _instance_unapply_static(self, instance, full_rollback = False):
		super(SchedulerPlugin, self)._instance_unapply_static(instance, full_rollback)
		if self._daemon and instance._runtime_tuning:
			instance._terminate.set()
			instance._thread.join()
		self._restore_ps_affinity()

	def _add_pid(self, instance, pid, r):
		try:
			cmd = self._get_cmdline(pid)
		except (OSError, IOError) as e:
			if e.errno == errno.ENOENT \
					or e.errno == errno.ESRCH:
				log.debug("Failed to get cmdline of PID %d, the task vanished."
						% pid)
			else:
				log.error("Failed to get cmdline of PID %d: %s"
						% (pid, e))
			return
		v = self._cmd.re_lookup(instance._sched_lookup, cmd, r)
		if v is not None and not pid in self._scheduler_original:
			log.debug("tuning new process '%s' with PID '%d' by '%s'" % (cmd, pid, str(v)))
			(sched, prio, affinity) = v
			self._tune_process(pid, cmd, sched, prio,
					affinity)
			self._storage.set(self._scheduler_storage_key,
					self._scheduler_original)

	def _remove_pid(self, instance, pid):
		if pid in self._scheduler_original:
			del self._scheduler_original[pid]
			log.debug("removed PID %d from the rollback database" % pid)
			self._storage.set(self._scheduler_storage_key,
					self._scheduler_original)

	def _thread_code(self, instance):
		r = self._cmd.re_lookup_compile(instance._sched_lookup)
		poll = select.poll()
		# Store the file objects in a local variable so that they don't
		# go out of scope too soon. This is a workaround for
		# python3-perf bug rhbz#1659445.
		fds = instance._evlist.get_pollfd()
		for fd in fds:
			poll.register(fd)
		while not instance._terminate.is_set():
			# timeout to poll in milliseconds
			if len(poll.poll(self._sleep_interval * 1000)) > 0 and not instance._terminate.is_set():
				read_events = True
				while read_events:
					read_events = False
					for cpu in self._cpus:
						event = instance._evlist.read_on_cpu(cpu)
						if event:
							read_events = True
							if event.type == perf.RECORD_COMM:
								self._add_pid(instance, int(event.tid), r)
							elif event.type == perf.RECORD_EXIT:
								self._remove_pid(instance, int(event.tid))

	@command_custom("ps_whitelist", per_device = False)
	def _ps_whitelist(self, enabling, value, verify, ignore_missing):
		# currently unsupported
		if verify:
			return None
		if enabling and value is not None:
			self._ps_whitelist = "|".join(["(%s)" % v for v in re.split(r"(?<!\\);", str(value))])

	@command_custom("ps_blacklist", per_device = False)
	def _ps_blacklist(self, enabling, value, verify, ignore_missing):
		# currently unsupported
		if verify:
			return None
		if enabling and value is not None:
			self._ps_blacklist = "|".join(["(%s)" % v for v in re.split(r"(?<!\\);", str(value))])

	# Raises OSError
	# Raises SystemError with old (pre-0.4) python-schedutils
	# instead of OSError
	# If PID doesn't exist, errno == ESRCH
	def _get_affinity(self, pid):
		res = schedutils.get_affinity(pid)
		log.debug("Read affinity '%s' of PID %d" % (res, pid))
		return res

	def _set_affinity(self, pid, affinity):
		log.debug("Setting CPU affinity of PID %d to '%s'." % (pid, affinity))
		try:
			schedutils.set_affinity(pid, affinity)
			return True
		# Workaround for old python-schedutils (pre-0.4) which
		# incorrectly raised SystemError instead of OSError
		except (SystemError, OSError) as e:
			if hasattr(e, "errno") and e.errno == errno.ESRCH:
				log.debug("Failed to set affinity of PID %d, the task vanished."
						% pid)
			else:
				res = self._affinity_changeable(pid)
				if res == 1 or res == -2:
					log.error("Failed to set affinity of PID %d to '%s': %s"
							% (pid, affinity, e))
			return False

	# returns intersection of affinity1 with affinity2, if intersection is empty it returns affinity3
	def _get_intersect_affinity(self, affinity1, affinity2, affinity3):
		aff = set(affinity1).intersection(set(affinity2))
		if aff:
			return list(aff)
		return affinity3

	def _set_all_obj_affinity(self, objs, affinity, threads = False):
		psl = [v for v in objs if re.search(self._ps_whitelist,
				self._get_stat_comm(v)) is not None]
		if self._ps_blacklist != "":
			psl = [v for v in psl if re.search(self._ps_blacklist,
					self._get_stat_comm(v)) is None]
		psd = dict([(v.pid, v) for v in psl])
		for pid in psd:
			try:
				cmd = self._get_cmdline(psd[pid])
			except (OSError, IOError) as e:
				if e.errno == errno.ENOENT \
						or e.errno == errno.ESRCH:
					log.debug("Failed to get cmdline of PID %d, the task vanished."
							% pid)
				else:
					log.error("Refusing to set affinity of PID %d, failed to get its cmdline: %s"
							% (pid, e))
				continue
			cont = self._tune_process_affinity(pid, affinity,
					intersect = True)
			if not cont:
				continue
			if pid in self._scheduler_original:
				self._scheduler_original[pid].cmdline = cmd
			# process threads
			if not threads and "threads" in psd[pid]:
				self._set_all_obj_affinity(
						psd[pid]["threads"].values(),
						affinity, True)

	def _get_stat_comm(self, o):
		try:
			return o["stat"]["comm"]
		except (OSError, IOError, KeyError):
			return ""

	def _set_ps_affinity(self, affinity):
		try:
			ps = procfs.pidstats()
			ps.reload_threads()
			self._set_all_obj_affinity(ps.values(), affinity, False)
		except (OSError, IOError) as e:
			log.error("error applying tuning, cannot get information about running processes: %s"
					% e)

	def _set_irq_affinity(self, irq, affinity, restoring):
		try:
			affinity_hex = self._cmd.cpulist2hex(affinity)
			log.debug("Setting SMP affinity of IRQ %s to '%s'"
					% (irq, affinity_hex))
			filename = "/proc/irq/%s/smp_affinity" % irq
			with open(filename, "w") as f:
				f.write(affinity_hex)
			return True
		except (OSError, IOError) as e:
			# EIO is returned by
			# kernel/irq/proc.c:write_irq_affinity() if changing
			# the affinity is not supported
			# (at least on kernels 3.10 and 4.18)
			if hasattr(e, "errno") and e.errno == errno.EIO \
					and not restoring:
				log.debug("Setting SMP affinity of IRQ %s is not supported"
						% irq)
			else:
				log.error("Failed to set SMP affinity of IRQ %s to '%s': %s"
						% (irq, affinity_hex, e))
			return False

	def _set_default_irq_affinity(self, affinity):
		try:
			affinity_hex = self._cmd.cpulist2hex(affinity)
			log.debug("Setting default SMP IRQ affinity to '%s'"
					% affinity_hex)
			with open("/proc/irq/default_smp_affinity", "w") as f:
				f.write(affinity_hex)
		except (OSError, IOError) as e:
			log.error("Failed to set default SMP IRQ affinity to '%s': %s"
					% (affinity_hex, e))

	def _set_all_irq_affinity(self, affinity):
		irq_original = IRQAffinities()
		irqs = procfs.interrupts()
		for irq in irqs.keys():
			try:
				prev_affinity = irqs[irq]["affinity"]
				log.debug("Read affinity of IRQ '%s': '%s'"
						% (irq, prev_affinity))
			except KeyError:
				continue
			_affinity = self._get_intersect_affinity(prev_affinity, affinity, affinity)
			if set(_affinity) == set(prev_affinity):
				continue
			if self._set_irq_affinity(irq, _affinity, False):
				irq_original.irqs[irq] = prev_affinity

		# default affinity
		prev_affinity_hex = self._cmd.read_file("/proc/irq/default_smp_affinity")
		prev_affinity = self._cmd.hex2cpulist(prev_affinity_hex)
		_affinity = self._get_intersect_affinity(prev_affinity, affinity, affinity)
		self._set_default_irq_affinity(_affinity)
		irq_original.default = prev_affinity
		self._storage.set(self._irq_storage_key, irq_original)

	def _restore_all_irq_affinity(self):
		irq_original = self._storage.get(self._irq_storage_key, None)
		if irq_original is None:
			return
		for irq, affinity in irq_original.irqs.items():
			self._set_irq_affinity(irq, affinity, True)
		affinity = irq_original.default
		self._set_default_irq_affinity(affinity)
		self._storage.unset(self._irq_storage_key)

	def _verify_irq_affinity(self, irq_description, correct_affinity,
			current_affinity):
		res = set(current_affinity).issubset(set(correct_affinity))
		if res:
			log.info(consts.STR_VERIFY_PROFILE_VALUE_OK
					% (irq_description, current_affinity))
		else:
			log.error(consts.STR_VERIFY_PROFILE_VALUE_FAIL
					% (irq_description, current_affinity,
					correct_affinity))
		return res

	def _verify_all_irq_affinity(self, correct_affinity):
		irqs = procfs.interrupts()
		res = True
		for irq in irqs.keys():
			try:
				current_affinity = irqs[irq]["affinity"]
				log.debug("Read SMP affinity of IRQ '%s': '%s'"
						% (irq, current_affinity))
				irq_description = "SMP affinity of IRQ %s" % irq
				if not self._verify_irq_affinity(
						irq_description,
						correct_affinity,
						current_affinity):
					res = False
			except KeyError:
				continue

		current_affinity_hex = self._cmd.read_file(
				"/proc/irq/default_smp_affinity")
		current_affinity = self._cmd.hex2cpulist(current_affinity_hex)
		if not self._verify_irq_affinity("default IRQ SMP affinity",
				current_affinity, correct_affinity):
			res = False
		return res

	@command_custom("isolated_cores", per_device = False, priority = 10)
	def _isolated_cores(self, enabling, value, verify, ignore_missing):
		affinity = None
		if value is not None:
			isolated = set(self._cmd.cpulist_unpack(value))
			present = set(self._cpus)
			if isolated.issubset(present):
				affinity = list(present - isolated)
			else:
				str_cpus = ",".join([str(x) for x in self._cpus])
				log.error("Invalid isolated_cores specified, '%s' does not match available cores '%s'"
						% (value, str_cpus))
		if (enabling or verify) and affinity is None:
			return None
		# currently only IRQ affinity verification is supported
		if verify:
			return self._verify_all_irq_affinity(affinity)
		elif enabling:
			self._set_ps_affinity(affinity)
			self._set_all_irq_affinity(affinity)
		else:
			# Restoring processes' affinity is done in
			# _instance_unapply_static()
			self._restore_all_irq_affinity()