Mini Shell
import errno
from . import hotplug
from .decorators import *
import tuned.logs
import tuned.consts as consts
from tuned.utils.commands import commands
import os
import re
log = tuned.logs.get()
class DiskPlugin(hotplug.Plugin):
"""
`disk`::
Plug-in for tuning various block device options. This plug-in can also
dynamically change the advanced power management and spindown timeout
setting for a drive according to the current drive utilization. The
dynamic tuning is controlled by the [option]`dynamic` and the global
[option]`dynamic_tuning` option in `tuned-main.conf`.
+
The disk plug-in operates on all supported block devices unless a
comma separated list of [option]`devices` is passed to it.
+
.Operate only on the sda block device
====
----
[disk]
# Comma separated list of devices, all devices if commented out.
devices=sda
----
====
+
The [option]`elevator` option sets the Linux I/O scheduler.
+
.Use the bfq I/O scheduler on xvda block device
====
----
[disk]
device=xvda
elevator=bfq
----
====
+
The [option]`scheduler_quantum` option only applies to the CFQ I/O
scheduler. It defines the number of I/O requests that CFQ sends to
one device at one time, essentially limiting queue depth. The default
value is 8 requests. The device being used may support greater queue
depth, but increasing the value of quantum will also increase latency,
especially for large sequential write work loads.
+
The [option]`apm` option sets the Advanced Power Management feature
on drives that support it. It corresponds to using the `-B` option of
the `hdparm` utility. The [option]`spindown` option puts the drive
into idle (low-power) mode, and also sets the standby (spindown)
timeout for the drive. It corresponds to using `-S` option of the
`hdparm` utility.
+
.Use a medium-agressive power management with spindown
====
----
[disk]
apm=128
spindown=6
----
====
+
The [option]`readahead` option controls how much extra data the
operating system reads from disk when performing sequential
I/O operations. Increasing the `readahead` value might improve
performance in application environments where sequential reading of
large files takes place. The default unit for readahead is KiB. This
can be adjusted to sectors by specifying the suffix 's'. If the
suffix is specified, there must be at least one space between the
number and suffix (for example, `readahead=8192 s`).
+
.Set the `readahead` to 4MB unless already set to a higher value
====
----
[disk]
readahead=>4096
----
====
The disk readahead value can be multiplied by the constant
specified by the [option]`readahead_multiply` option.
"""
def __init__(self, *args, **kwargs):
super(DiskPlugin, self).__init__(*args, **kwargs)
self._power_levels = [254, 225, 195, 165, 145, 125, 105, 85, 70, 55, 30, 20]
self._spindown_levels = [0, 250, 230, 210, 190, 170, 150, 130, 110, 90, 70, 60]
self._levels = len(self._power_levels)
self._level_steps = 6
self._load_smallest = 0.01
self._cmd = commands()
def _init_devices(self):
super(DiskPlugin, self)._init_devices()
self._devices_supported = True
self._use_hdparm = True
self._free_devices = set()
self._hdparm_apm_devices = set()
for device in self._hardware_inventory.get_devices("block"):
if self._device_is_supported(device):
self._free_devices.add(device.sys_name)
if self._use_hdparm and self._is_hdparm_apm_supported(device.sys_name):
self._hdparm_apm_devices.add(device.sys_name)
self._assigned_devices = set()
def _get_device_objects(self, devices):
return [self._hardware_inventory.get_device("block", x) for x in devices]
def _is_hdparm_apm_supported(self, device):
(rc, out, err_msg) = self._cmd.execute(["hdparm", "-C", "/dev/%s" % device], \
no_errors = [errno.ENOENT], return_err=True)
if rc == -errno.ENOENT:
log.warn("hdparm command not found, ignoring for other devices")
self._use_hdparm = False
return False
elif rc:
log.info("Device '%s' not supported by hdparm" % device)
log.debug("(rc: %s, msg: '%s')" % (rc, err_msg))
return False
elif "unknown" in out:
log.info("Driver for device '%s' does not support apm command" % device)
return False
return True
@classmethod
def _device_is_supported(cls, device):
return device.device_type == "disk" and \
device.attributes.get("removable", None) == b"0" and \
(device.parent is None or \
device.parent.subsystem in ["scsi", "virtio", "xen", "nvme"])
def _hardware_events_init(self):
self._hardware_inventory.subscribe(self, "block", self._hardware_events_callback)
def _hardware_events_cleanup(self):
self._hardware_inventory.unsubscribe(self)
def _hardware_events_callback(self, event, device):
if self._device_is_supported(device) or event == "remove":
super(DiskPlugin, self)._hardware_events_callback(event, device)
def _added_device_apply_tuning(self, instance, device_name):
if instance._load_monitor is not None:
instance._load_monitor.add_device(device_name)
super(DiskPlugin, self)._added_device_apply_tuning(instance, device_name)
def _removed_device_unapply_tuning(self, instance, device_name):
if instance._load_monitor is not None:
instance._load_monitor.remove_device(device_name)
super(DiskPlugin, self)._removed_device_unapply_tuning(instance, device_name)
@classmethod
def _get_config_options(cls):
return {
"dynamic" : True, # FIXME: do we want this default?
"elevator" : None,
"apm" : None,
"spindown" : None,
"readahead" : None,
"readahead_multiply" : None,
"scheduler_quantum" : None,
}
@classmethod
def _get_config_options_used_by_dynamic(cls):
return [
"apm",
"spindown",
]
def _instance_init(self, instance):
instance._has_static_tuning = True
self._apm_errcnt = 0
self._spindown_errcnt = 0
if self._option_bool(instance.options["dynamic"]):
instance._has_dynamic_tuning = True
instance._load_monitor = \
self._monitors_repository.create(
"disk", instance.assigned_devices)
instance._device_idle = {}
instance._stats = {}
instance._idle = {}
instance._spindown_change_delayed = {}
else:
instance._has_dynamic_tuning = False
instance._load_monitor = None
def _instance_cleanup(self, instance):
if instance._load_monitor is not None:
self._monitors_repository.delete(instance._load_monitor)
instance._load_monitor = None
def _update_errcnt(self, rc, spindown):
if spindown:
s = "spindown"
cnt = self._spindown_errcnt
else:
s = "apm"
cnt = self._apm_errcnt
if cnt >= consts.ERROR_THRESHOLD:
return
if rc == 0:
cnt = 0
elif rc == -errno.ENOENT:
self._spindown_errcnt = self._apm_errcnt = consts.ERROR_THRESHOLD + 1
log.warn("hdparm command not found, ignoring future set_apm / set_spindown commands")
return
else:
cnt += 1
if cnt == consts.ERROR_THRESHOLD:
log.info("disabling set_%s command: too many consecutive errors" % s)
if spindown:
self._spindown_errcnt = cnt
else:
self._apm_errcnt = cnt
def _change_spindown(self, instance, device, new_spindown_level):
log.debug("changing spindown to %d" % new_spindown_level)
(rc, out) = self._cmd.execute(["hdparm", "-S%d" % new_spindown_level, "/dev/%s" % device], no_errors = [errno.ENOENT])
self._update_errcnt(rc, True)
instance._spindown_change_delayed[device] = False
def _drive_spinning(self, device):
(rc, out) = self._cmd.execute(["hdparm", "-C", "/dev/%s" % device], no_errors = [errno.ENOENT])
return not "standby" in out and not "sleeping" in out
def _instance_update_dynamic(self, instance, device):
if not device in self._hdparm_apm_devices:
return
load = instance._load_monitor.get_device_load(device)
if load is None:
return
if not device in instance._stats:
self._init_stats_and_idle(instance, device)
self._update_stats(instance, device, load)
self._update_idle(instance, device)
stats = instance._stats[device]
idle = instance._idle[device]
# level change decision
if idle["level"] + 1 < self._levels and idle["read"] >= self._level_steps and idle["write"] >= self._level_steps:
level_change = 1
elif idle["level"] > 0 and (idle["read"] == 0 or idle["write"] == 0):
level_change = -1
else:
level_change = 0
# change level if decided
if level_change != 0:
idle["level"] += level_change
new_power_level = self._power_levels[idle["level"]]
new_spindown_level = self._spindown_levels[idle["level"]]
log.debug("tuning level changed to %d" % idle["level"])
if self._spindown_errcnt < consts.ERROR_THRESHOLD:
if not self._drive_spinning(device) and level_change > 0:
log.debug("delaying spindown change to %d, drive has already spun down" % new_spindown_level)
instance._spindown_change_delayed[device] = True
else:
self._change_spindown(instance, device, new_spindown_level)
if self._apm_errcnt < consts.ERROR_THRESHOLD:
log.debug("changing APM_level to %d" % new_power_level)
(rc, out) = self._cmd.execute(["hdparm", "-B%d" % new_power_level, "/dev/%s" % device], no_errors = [errno.ENOENT])
self._update_errcnt(rc, False)
elif instance._spindown_change_delayed[device] and self._drive_spinning(device):
new_spindown_level = self._spindown_levels[idle["level"]]
self._change_spindown(instance, device, new_spindown_level)
log.debug("%s load: read %0.2f, write %0.2f" % (device, stats["read"], stats["write"]))
log.debug("%s idle: read %d, write %d, level %d" % (device, idle["read"], idle["write"], idle["level"]))
def _init_stats_and_idle(self, instance, device):
instance._stats[device] = { "new": 11 * [0], "old": 11 * [0], "max": 11 * [1] }
instance._idle[device] = { "level": 0, "read": 0, "write": 0 }
instance._spindown_change_delayed[device] = False
def _update_stats(self, instance, device, new_load):
instance._stats[device]["old"] = old_load = instance._stats[device]["new"]
instance._stats[device]["new"] = new_load
# load difference
diff = [new_old[0] - new_old[1] for new_old in zip(new_load, old_load)]
instance._stats[device]["diff"] = diff
# adapt maximum expected load if the difference is higher
old_max_load = instance._stats[device]["max"]
max_load = [max(pair) for pair in zip(old_max_load, diff)]
instance._stats[device]["max"] = max_load
# read/write ratio
instance._stats[device]["read"] = float(diff[1]) / float(max_load[1])
instance._stats[device]["write"] = float(diff[5]) / float(max_load[5])
def _update_idle(self, instance, device):
# increase counter if there is no load, otherwise reset the counter
for operation in ["read", "write"]:
if instance._stats[device][operation] < self._load_smallest:
instance._idle[device][operation] += 1
else:
instance._idle[device][operation] = 0
def _instance_apply_dynamic(self, instance, device):
# At the moment we support dynamic tuning just for devices compatible with hdparm apm commands
# If in future will be added new functionality not connected to this command,
# it is needed to change it here
if device not in self._hdparm_apm_devices:
log.info("There is no dynamic tuning available for device '%s' at time" % device)
else:
super(DiskPlugin, self)._instance_apply_dynamic(instance, device)
def _instance_unapply_dynamic(self, instance, device):
pass
def _sysfs_path(self, device, suffix, prefix = "/sys/block/"):
if "/" in device:
dev = os.path.join(prefix, device.replace("/", "!"), suffix)
if os.path.exists(dev):
return dev
return os.path.join(prefix, device, suffix)
def _elevator_file(self, device):
return self._sysfs_path(device, "queue/scheduler")
@command_set("elevator", per_device=True)
def _set_elevator(self, value, device, sim, remove):
sys_file = self._elevator_file(device)
if not sim:
self._cmd.write_to_file(sys_file, value, \
no_error = [errno.ENOENT] if remove else False)
return value
@command_get("elevator")
def _get_elevator(self, device, ignore_missing=False):
sys_file = self._elevator_file(device)
# example of scheduler file content:
# noop deadline [cfq]
return self._cmd.get_active_option(self._cmd.read_file(sys_file, no_error=ignore_missing))
@command_set("apm", per_device=True)
def _set_apm(self, value, device, sim, remove):
if device not in self._hdparm_apm_devices:
if not sim:
log.info("apm option is not supported for device '%s'" % device)
return None
else:
return str(value)
if self._apm_errcnt < consts.ERROR_THRESHOLD:
if not sim:
(rc, out) = self._cmd.execute(["hdparm", "-B", str(value), "/dev/" + device], no_errors = [errno.ENOENT])
self._update_errcnt(rc, False)
return str(value)
else:
return None
@command_get("apm")
def _get_apm(self, device, ignore_missing=False):
if device not in self._hdparm_apm_devices:
if not ignore_missing:
log.info("apm option is not supported for device '%s'" % device)
return None
value = None
err = False
(rc, out) = self._cmd.execute(["hdparm", "-B", "/dev/" + device], no_errors = [errno.ENOENT])
if rc == -errno.ENOENT:
return None
elif rc != 0:
err = True
else:
m = re.match(r".*=\s*(\d+).*", out, re.S)
if m:
try:
value = int(m.group(1))
except ValueError:
err = True
if err:
log.error("could not get current APM settings for device '%s'" % device)
return value
@command_set("spindown", per_device=True)
def _set_spindown(self, value, device, sim, remove):
if device not in self._hdparm_apm_devices:
if not sim:
log.info("spindown option is not supported for device '%s'" % device)
return None
else:
return str(value)
if self._spindown_errcnt < consts.ERROR_THRESHOLD:
if not sim:
(rc, out) = self._cmd.execute(["hdparm", "-S", str(value), "/dev/" + device], no_errors = [errno.ENOENT])
self._update_errcnt(rc, True)
return str(value)
else:
return None
@command_get("spindown")
def _get_spindown(self, device, ignore_missing=False):
if device not in self._hdparm_apm_devices:
if not ignore_missing:
log.info("spindown option is not supported for device '%s'" % device)
return None
# There's no way how to get current/old spindown value, hardcoding vendor specific 253
return 253
def _readahead_file(self, device):
return self._sysfs_path(device, "queue/read_ahead_kb")
def _parse_ra(self, value):
val = str(value).split(None, 1)
try:
v = int(val[0])
except ValueError:
return None
if len(val) > 1 and val[1][0] == "s":
# v *= 512 / 1024
v /= 2
return v
@command_set("readahead", per_device=True)
def _set_readahead(self, value, device, sim, remove):
sys_file = self._readahead_file(device)
val = self._parse_ra(value)
if val is None:
log.error("Invalid readahead value '%s' for device '%s'" % (value, device))
else:
if not sim:
self._cmd.write_to_file(sys_file, "%d" % val, \
no_error = [errno.ENOENT] if remove else False)
return val
@command_get("readahead")
def _get_readahead(self, device, ignore_missing=False):
sys_file = self._readahead_file(device)
value = self._cmd.read_file(sys_file, no_error=ignore_missing).strip()
if len(value) == 0:
return None
return int(value)
@command_custom("readahead_multiply", per_device=True)
def _multiply_readahead(self, enabling, multiplier, device, verify, ignore_missing):
if verify:
return None
storage_key = self._storage_key(
command_name = "readahead_multiply",
device_name = device)
if enabling:
old_readahead = self._get_readahead(device)
if old_readahead is None:
return
new_readahead = int(float(multiplier) * old_readahead)
self._storage.set(storage_key, old_readahead)
self._set_readahead(new_readahead, device, False)
else:
old_readahead = self._storage.get(storage_key)
if old_readahead is None:
return
self._set_readahead(old_readahead, device, False)
self._storage.unset(storage_key)
def _scheduler_quantum_file(self, device):
return self._sysfs_path(device, "queue/iosched/quantum")
@command_set("scheduler_quantum", per_device=True)
def _set_scheduler_quantum(self, value, device, sim, remove):
sys_file = self._scheduler_quantum_file(device)
if not sim:
self._cmd.write_to_file(sys_file, "%d" % int(value), \
no_error = [errno.ENOENT] if remove else False)
return value
@command_get("scheduler_quantum")
def _get_scheduler_quantum(self, device, ignore_missing=False):
sys_file = self._scheduler_quantum_file(device)
value = self._cmd.read_file(sys_file, no_error=ignore_missing).strip()
if len(value) == 0:
if not ignore_missing:
log.info("disk_scheduler_quantum option is not supported for device '%s'" % device)
return None
return int(value)
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