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neutron/neutron/agent/linux/tc_lib.py

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# Copyright 2016 OVH SAS
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import math
import re
from neutron_lib import exceptions
from neutron_lib.exceptions import qos as qos_exc
from neutron_lib.services.qos import constants as qos_consts
from oslo_log import log as logging
from pyroute2.netlink import rtnl
from pyroute2.netlink.rtnl.tcmsg import common as rtnl_common
from neutron._i18n import _
from neutron.agent.linux import ip_lib
from neutron.common import constants
from neutron.common import utils
from neutron.privileged.agent.linux import tc_lib as priv_tc_lib
LOG = logging.getLogger(__name__)
INGRESS_QDISC_ID = "ffff:"
MAX_MTU_VALUE = 65535
LATENCY_UNIT = "ms"
BW_LIMIT_UNIT = "kbit" # kilobits per second in tc's notation
BURST_UNIT = "kbit" # kilobits in tc's notation
# Those are RATES (bits per second) and SIZE (bytes) unit names from tc manual
UNITS = {
"k": 1,
"m": 2,
"g": 3,
"t": 4
}
filters_pattern = re.compile(r"police \w+ rate (\w+) burst (\w+)")
tbf_pattern = re.compile(
r"qdisc (\w+) \w+: \w+ refcnt \d rate (\w+) burst (\w+) \w*")
TC_QDISC_TYPES = ['htb', 'tbf', 'ingress']
TC_QDISC_PARENT = {'root': rtnl.TC_H_ROOT,
'ingress': rtnl.TC_H_INGRESS}
TC_QDISC_PARENT_NAME = {v: k for k, v in TC_QDISC_PARENT.items()}
class InvalidKernelHzValue(exceptions.NeutronException):
message = _("Kernel HZ value %(value)s is not valid. This value must be "
"greater than 0.")
class InvalidUnit(exceptions.NeutronException):
message = _("Unit name '%(unit)s' is not valid.")
def convert_to_kilobits(value, base):
value = value.lower()
if "bit" in value:
input_in_bits = True
value = value.replace("bit", "")
else:
input_in_bits = False
value = value.replace("b", "")
# if it is now bare number then it is in bits, so we return it simply
if value.isdigit():
value = int(value)
if input_in_bits:
return utils.bits_to_kilobits(value, base)
else:
bits_value = utils.bytes_to_bits(value)
return utils.bits_to_kilobits(bits_value, base)
unit = value[-1:]
if unit not in UNITS.keys():
raise InvalidUnit(unit=unit)
val = int(value[:-1])
if input_in_bits:
bits_value = val * (base ** UNITS[unit])
else:
bits_value = utils.bytes_to_bits(val * (base ** UNITS[unit]))
return utils.bits_to_kilobits(bits_value, base)
def _get_attr(pyroute2_obj, attr_name):
rule_attrs = pyroute2_obj.get('attrs', [])
for attr in (attr for attr in rule_attrs if attr[0] == attr_name):
return attr[1]
return
def _get_tbf_burst_value(rate, burst_limit, kernel_hz):
min_burst_value = float(rate) / float(kernel_hz)
return max(min_burst_value, burst_limit)
def _calc_burst(rate, buffer):
"""Calculate burst rate
:param rate: (int) rate in bytes per second.
:param buffer: (int) buffer size in bytes.
:return: (int) burst in bytes
"""
# NOTE(ralonsoh): this function is based in
# pyroute2.netlink.rtnl.tcmsg.common.calc_xmittime
return int(math.ceil(
float(buffer * rate) /
(rtnl_common.TIME_UNITS_PER_SEC * rtnl_common.tick_in_usec)))
def _calc_latency_ms(limit, burst, rate):
"""Calculate latency value, in ms
:param limit: (int) pyroute2 limit value
:param burst: (int) burst in bytes
:param rate: (int) maximum bandwidth in kbytes per second
:return: (int) latency, in ms
"""
return int(math.ceil(
float((limit - burst) * rtnl_common.TIME_UNITS_PER_SEC) /
(rate * 1000)))
def _handle_from_hex_to_string(handle):
"""Convert TC handle from hex to string
:param handle: (int) TC handle
:return: (string) handle formatted to string: 0xMMMMmmmm -> "M:m"
"""
minor = str(handle & 0xFFFF)
major = str((handle & 0xFFFF0000) >> 16)
return ':'.join([major, minor])
class TcCommand(ip_lib.IPDevice):
def __init__(self, name, kernel_hz, namespace=None):
if kernel_hz <= 0:
raise InvalidKernelHzValue(value=kernel_hz)
super(TcCommand, self).__init__(name, namespace=namespace)
self.kernel_hz = kernel_hz
def _execute_tc_cmd(self, cmd, **kwargs):
cmd = ['tc'] + cmd
ip_wrapper = ip_lib.IPWrapper(self.namespace)
return ip_wrapper.netns.execute(cmd, run_as_root=True, **kwargs)
@staticmethod
def get_ingress_qdisc_burst_value(bw_limit, burst_limit):
"""Return burst value used in ingress qdisc.
If burst value is not specified given than it will be set to default
rate to ensure that limit for TCP traffic will work well
"""
if not burst_limit:
return float(bw_limit) * qos_consts.DEFAULT_BURST_RATE
return burst_limit
def get_filters_bw_limits(self, qdisc_id=INGRESS_QDISC_ID):
cmd = ['filter', 'show', 'dev', self.name, 'parent', qdisc_id]
cmd_result = self._execute_tc_cmd(cmd)
if not cmd_result:
return None, None
for line in cmd_result.split("\n"):
m = filters_pattern.match(line.strip())
if m:
# NOTE(slaweq): because tc is giving bw limit in SI units
# we need to calculate it as 1000bit = 1kbit:
bw_limit = convert_to_kilobits(m.group(1), constants.SI_BASE)
# NOTE(slaweq): because tc is giving burst limit in IEC units
# we need to calculate it as 1024bit = 1kbit:
burst_limit = convert_to_kilobits(
m.group(2), constants.IEC_BASE)
return bw_limit, burst_limit
return None, None
def get_tbf_bw_limits(self):
qdiscs = list_tc_qdiscs(self.name, namespace=self.namespace)
if not qdiscs:
return None, None
qdisc = qdiscs[0]
if qdisc['qdisc_type'] != 'tbf':
return None, None
return qdisc['max_kbps'], qdisc['burst_kb']
def set_filters_bw_limit(self, bw_limit, burst_limit):
"""Set ingress qdisc and filter for police ingress traffic on device
This will allow to police traffic incoming to interface. It
means that it is fine to limit egress traffic from instance point of
view.
"""
# because replace of tc filters is not working properly and it's adding
# new filters each time instead of replacing existing one first old
# ingress qdisc should be deleted and then added new one so update will
# be called to do that:
return self.update_filters_bw_limit(bw_limit, burst_limit)
def set_tbf_bw_limit(self, bw_limit, burst_limit, latency_value):
"""Set/update token bucket filter qdisc on device
This will allow to limit speed of packets going out from interface. It
means that it is fine to limit ingress traffic from instance point of
view.
"""
return add_tc_qdisc(self.name, 'tbf', parent='root',
max_kbps=bw_limit, burst_kb=burst_limit,
latency_ms=latency_value, kernel_hz=self.kernel_hz,
namespace=self.namespace)
def update_filters_bw_limit(self, bw_limit, burst_limit):
self.delete_filters_bw_limit()
add_tc_qdisc(self.name, 'ingress', namespace=self.namespace)
return self._add_policy_filter(bw_limit, burst_limit)
def delete_filters_bw_limit(self):
# NOTE(slaweq): For limit traffic egress from instance we need to use
# qdisc "ingress" because it is ingress traffic from interface POV:
self._delete_qdisc("ingress")
def delete_tbf_bw_limit(self):
self._delete_qdisc("root")
def _delete_qdisc(self, qdisc_name):
cmd = ['qdisc', 'del', 'dev', self.name, qdisc_name]
# Return_code=2 is fine because it means
# "RTNETLINK answers: No such file or directory" what is fine when we
# are trying to delete qdisc
# Return_code=1 means "RTNETLINK answers: Cannot find device <device>".
# If the device doesn't exist, the qdisc is already deleted.
return self._execute_tc_cmd(cmd, extra_ok_codes=[1, 2])
def _add_policy_filter(self, bw_limit, burst_limit,
qdisc_id=INGRESS_QDISC_ID):
rate_limit = "%s%s" % (bw_limit, BW_LIMIT_UNIT)
burst = "%s%s" % (
self.get_ingress_qdisc_burst_value(bw_limit, burst_limit),
BURST_UNIT
)
# NOTE(slaweq): it is made in exactly same way how openvswitch is doing
# it when configuing ingress traffic limit on port. It can be found in
# lib/netdev-linux.c#L4698 in openvswitch sources:
cmd = [
'filter', 'add', 'dev', self.name,
'parent', qdisc_id, 'protocol', 'all',
'prio', '49', 'basic', 'police',
'rate', rate_limit,
'burst', burst,
'mtu', MAX_MTU_VALUE,
'drop']
return self._execute_tc_cmd(cmd)
def add_tc_qdisc(device, qdisc_type, parent=None, handle=None, latency_ms=None,
max_kbps=None, burst_kb=None, kernel_hz=None,
namespace=None):
"""Add/replace a TC qdisc on a device
pyroute2 input parameters:
- rate (min bw): bytes/second
- burst: bytes
- latency: us
:param device: (string) device name
:param qdisc_type: (string) qdisc type (TC_QDISC_TYPES)
:param parent: (string) qdisc parent class ('root', '2:10')
:param handle: (string, int) (required for HTB) major handler identifier
(0xffff0000, '1', '1:', '1:0') [1]
:param latency_ms: (string, int) (required for TBF) latency time in ms
:param max_kbps: (string, int) (required for TBF) maximum bandwidth in
kbits per second.
:param burst_kb: (string, int) (required for TBF) maximum bandwidth in
kbits.
:param kernel_hz: (string, int) (required for TBF) kernel HZ.
:param namespace: (string) (optional) namespace name
[1] https://lartc.org/howto/lartc.qdisc.classful.html
"""
if qdisc_type and qdisc_type not in TC_QDISC_TYPES:
raise qos_exc.TcLibQdiscTypeError(
qdisc_type=qdisc_type, supported_qdisc_types=TC_QDISC_TYPES)
args = {'kind': qdisc_type}
if qdisc_type in ['htb', 'ingress']:
if handle:
args['handle'] = str(handle).split(':')[0] + ':0'
elif qdisc_type == 'tbf':
if not latency_ms or not max_kbps or not kernel_hz:
raise qos_exc.TcLibQdiscNeededArguments(
qdisc_type=qdisc_type,
needed_arguments=['latency_ms', 'max_kbps', 'kernel_hz'])
args['burst'] = int(
_get_tbf_burst_value(max_kbps, burst_kb, kernel_hz) * 1024 / 8)
args['rate'] = int(max_kbps * 1024 / 8)
args['latency'] = latency_ms * 1000
if parent:
args['parent'] = rtnl.TC_H_ROOT if parent == 'root' else parent
priv_tc_lib.add_tc_qdisc(device, namespace=namespace, **args)
def list_tc_qdiscs(device, namespace=None):
"""List all TC qdiscs of a device
:param device: (string) device name
:param namespace: (string) (optional) namespace name
:return: (list) TC qdiscs
"""
qdiscs = priv_tc_lib.list_tc_qdiscs(device, namespace=namespace)
retval = []
for qdisc in qdiscs:
qdisc_attrs = {
'qdisc_type': _get_attr(qdisc, 'TCA_KIND'),
'parent': TC_QDISC_PARENT_NAME.get(
qdisc['parent'], _handle_from_hex_to_string(qdisc['parent'])),
'handle': _handle_from_hex_to_string(qdisc['handle'])}
if qdisc_attrs['qdisc_type'] == 'tbf':
tca_options = _get_attr(qdisc, 'TCA_OPTIONS')
tca_tbf_parms = _get_attr(tca_options, 'TCA_TBF_PARMS')
qdisc_attrs['max_kbps'] = int(tca_tbf_parms['rate'] * 8 / 1024)
burst_bytes = _calc_burst(tca_tbf_parms['rate'],
tca_tbf_parms['buffer'])
qdisc_attrs['burst_kb'] = int(burst_bytes * 8 / 1024)
qdisc_attrs['latency_ms'] = _calc_latency_ms(
tca_tbf_parms['limit'], burst_bytes, tca_tbf_parms['rate'])
retval.append(qdisc_attrs)
return retval
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