JezK

Edit File: plugin_irq.py

from . import hotplug from .decorators import * import tuned.consts as consts import tuned.logs import errno import os log = tuned.logs.get() # the plugin manages each IRQ as a "device" and keeps a IrqInfo object for it class IrqInfo(object): def __init__(self, irq): self.irq = irq self.device = "irq%s" % irq self.unchangeable = False self.original_affinity = None class IrqPlugin(hotplug.Plugin): r""" Allows tuning of IRQ affinities, and thus re-implements functionality already present in the `scheduler` plugin. However, this plugin offers more flexibility, as it allows tuning of individual interrupts with different affinities. When using the `irq` plugin, make sure to disable IRQ processing in the `scheduler` plugin by setting its option [option]`irq_process=false`. The plugin handles individual IRQs as devices and multiple plugin instances can be defined, each addressing different devices/irqs. The device names used by the plugin are `irq<n>`, where `<n>` is the IRQ number. The special device `DEFAULT` controls values written to `/proc/irq/default_smp_affinity`, which applies to all non-active IRQs. The option [option]`affinity` controls the IRQ affinity to be set. It is a string in "cpulist" format (such as `1,3-4`). If the configured affinity is empty, then the affinity of the respective IRQs is not touched. The option [option]`mode` is a string which can either be `set` (default) or `intersect`. In `set` mode the [option]`affinity` is always written as configured, whereas in `intersect` mode, the new affinity will be calculated as the intersection of the current and the configured affinity. If that intersection is empty, the configured affinity will be used. .Moving all IRQs to CPU0, except irq16, which is directed to CPU2 ==== ---- [irq_special] type=irq devices=irq16 affinity=2 [irq] affinity=0 ---- ==== """ def __init__(self, monitor_repository, storage_factory, hardware_inventory, device_matcher, device_matcher_udev, plugin_instance_factory, global_cfg, variables): super(IrqPlugin, self).__init__(monitor_repository, storage_factory, hardware_inventory, device_matcher, device_matcher_udev, plugin_instance_factory, global_cfg, variables) self._irqs = {} # # plugin-level methods: devices and plugin options # def _init_devices(self): """Read /proc/irq to collect devices """ self._devices_supported = True self._free_devices = set() self._assigned_devices = set() for i in os.listdir("/proc/irq"): p = os.path.join("/proc/irq", i) if os.path.isdir(p) and i.isdigit(): info = IrqInfo(i) self._irqs[i] = info self._free_devices.add(info.device) # add the virtual device for default_smp_affinity default_info = IrqInfo("DEFAULT") default_info.device = "DEFAULT" self._irqs["DEFAULT"] = default_info self._free_devices.add(default_info.device) @classmethod def _get_config_options(cls): return { "affinity": "", "mode": "set", } # # instance-level methods: implement the Instance interface # def _instance_init(self, instance): instance._has_static_tuning = True instance._has_dynamic_tuning = False affinity = self._variables.expand(instance.options.get("affinity")) affinity_list = self._cmd.cpulist_unpack(affinity) if len(affinity.strip()) == 0: # empty affinity in profile -> assume it's intentional log.info("Instance '%s' configured with empty affinity. Deactivating." % instance.name) instance._active = False elif len(affinity_list) == 0: # non-empty affinity string evaluates to empty list -> assume parse error log.error("Instance '%s' with invalid affinity '%s'. Deactivating." % (instance.name, affinity)) instance._active = False mode = self._variables.expand(instance.options.get("mode")) if mode not in ["set", "intersect"]: log.error("Invalid operating mode '%s' for instance '%s'. Using the default 'set' instead." % (mode, instance.name)) instance.options["mode"] = "set" def _instance_cleanup(self, instance): pass def _instance_apply_static(self, instance): log.debug("Applying IRQ affinities (%s)" % instance.name) super(IrqPlugin, self)._instance_apply_static(instance) def _instance_unapply_static(self, instance, rollback): log.debug("Unapplying IRQ affinities (%s)" % instance.name) super(IrqPlugin, self)._instance_unapply_static(instance, rollback) def _instance_verify_static(self, instance, ignore_missing, devices): log.debug("Verifying IRQ affinities (%s)" % instance.name) return super(IrqPlugin, self)._instance_verify_static(instance, ignore_missing, devices) # # "low-level" methods to get/set irq affinities # def _get_irq_affinity(self, irq): """Get current IRQ affinity from the kernel Args: irq (str): IRQ number (as string) or "DEFAULT" Returns: affinity (set): set of all CPUs that belong to the IRQ affinity mask, if reading of the affinity fails, an empty set is returned """ try: filename = "/proc/irq/default_smp_affinity" if irq == "DEFAULT" else "/proc/irq/%s/smp_affinity" % irq with open(filename, "r") as f: affinity_hex = f.readline().strip() return set(self._cmd.hex2cpulist(affinity_hex)) except (OSError, IOError) as e: log.debug("Failed to read SMP affinity of IRQ %s: %s" % (irq, e)) return set() def _set_irq_affinity(self, irq, affinity, restoring): """Set IRQ affinity in the kernel Args: irq (str): IRQ number (as string) or "DEFAULT" affinity (set): affinity mask as set of CPUs restoring (bool): are we rolling back a previous change? Returns: status (int): 0 on success, -2 if changing the affinity is not supported, -1 if some other error occurs """ try: affinity_hex = self._cmd.cpulist2hex(list(affinity)) log.debug("Setting SMP affinity of IRQ %s to '%s'" % (irq, affinity_hex)) filename = "/proc/irq/default_smp_affinity" if irq == "DEFAULT" else "/proc/irq/%s/smp_affinity" % irq with open(filename, "w") as f: f.write(affinity_hex) return 0 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) return -2 else: log.error("Failed to set SMP affinity of IRQ %s to '%s': %s" % (irq, affinity_hex, e)) return -1 # # "high-level" methods: apply tuning while saving original affinities # def _apply_irq_affinity(self, irqinfo, affinity, mode): """Apply IRQ affinity tuning Args: irqinfo (IrqInfo): IRQ that should be tuned affinity (set): desired affinity """ original = self._get_irq_affinity(irqinfo.irq) if mode == "intersect": # intersection of affinity and original, if that is empty fall back to configured affinity affinity = affinity & original or affinity if irqinfo.unchangeable or affinity == original: return res = self._set_irq_affinity(irqinfo.irq, affinity, False) if res == 0: if irqinfo.original_affinity is None: irqinfo.original_affinity = original elif res == -2: irqinfo.unchangeable = True def _restore_irq_affinity(self, irqinfo): """Restore IRQ affinity Args: irqinfo (IrqInfo): IRQ that should be restored """ if irqinfo.unchangeable or irqinfo.original_affinity is None: return self._set_irq_affinity(irqinfo.irq, irqinfo.original_affinity, True) irqinfo.original_affinity = None def _verify_irq_affinity(self, irqinfo, affinity, mode): """Verify IRQ affinity tuning Args: irqinfo (IrqInfo): IRQ that should be verified affinity (set): desired affinity Returns: status (bool): True if verification successful, False otherwise """ if irqinfo.unchangeable: return True affinity_description = "IRQ %s affinity" % irqinfo.irq desired_affinity = affinity desired_affinity_string = self._cmd.cpulist2string(self._cmd.cpulist_pack(list(desired_affinity))) current_affinity = self._get_irq_affinity(irqinfo.irq) current_affinity_string = self._cmd.cpulist2string(self._cmd.cpulist_pack(list(current_affinity))) if mode == "intersect": # In intersect mode, we don't use a strict comparison; it's sufficient # if the current affinity is a subset of the desired one desired_affinity_string = "subset of " + desired_affinity_string if ((mode == "intersect" and current_affinity <= desired_affinity) or (mode == "set" and current_affinity == desired_affinity)): log.info(consts.STR_VERIFY_PROFILE_VALUE_OK % (affinity_description, desired_affinity_string)) return True else: log.error(consts.STR_VERIFY_PROFILE_VALUE_FAIL % (affinity_description, current_affinity_string, desired_affinity_string)) return False # # command definitions: entry to device-specific tuning # @command_custom("mode", per_device=False, priority=-10) def _mode(self, enabling, value, verify, ignore_missing, instance): if (enabling or verify) and value is not None: # Store the operating mode of the current instance in the plugin # object, from where it is read by the "affinity" command. # This works because instances are processed sequentially by the engine. self._mode_val = value @command_custom("affinity", per_device=True) def _affinity(self, enabling, value, device, verify, ignore_missing, instance): irq = "DEFAULT" if device == "DEFAULT" else device[len("irq"):] if irq not in self._irqs: log.error("Unknown device: %s" % device) return None irqinfo = self._irqs[irq] if verify: affinity = set(self._cmd.cpulist_unpack(value)) return self._verify_irq_affinity(irqinfo, affinity, self._mode_val) if enabling: affinity = set(self._cmd.cpulist_unpack(value)) return self._apply_irq_affinity(irqinfo, affinity, self._mode_val) else: return self._restore_irq_affinity(irqinfo)