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# Copyright (c) 2021 Cisco and/or its affiliates.
# 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.
"""Linux scheduler util library"""
from resources.libraries.python.ssh import SSH
__all__ = [u"SchedUtils"]
class SchedUtils:
"""General class for any linux scheduler related methods/functions."""
@staticmethod
def set_vpp_scheduling_rr(node):
"""Set real-time scheduling attributes of VPP worker threads to
SCHED_RR with priority 1.
:param node: DUT node with running VPP.
:type node: dict
:raises RuntimeError: Failed to retrieve PID for VPP worker threads.
"""
ssh = SSH()
ssh.connect(node)
cmd = u"cat /proc/`pidof vpp`/task/*/stat | grep -i vpp_wk" \
u" | awk '{print $1}'"
for _ in range(3):
ret, out, _ = ssh.exec_command_sudo(cmd)
if ret == 0:
try:
if not out:
raise ValueError
except ValueError:
print(u"Reading VPP worker thread PID failed.")
else:
for pid in out.split(u"\n"):
if pid and pid[0] != u"#":
SchedUtils.set_proc_scheduling_rr(node, int(pid))
break
else:
raise RuntimeError(
u"Failed to retrieve PID for VPP worker threads."
)
@staticmethod
def set_proc_scheduling_rr(node, pid, priority=1):
"""Set real-time scheduling of a process to SCHED_RR with priority for
specified PID.
:param node: Node where to apply scheduling changes.
:param pid: Process ID.
:param priority: Realtime priority in range 1-99. Default is 1.
:type node: dict
:type pid: int
:type priority: int
:raises ValueError: Parameters out of allowed ranges.
:raises RuntimeError: Failed to set policy for PID.
"""
ssh = SSH()
ssh.connect(node)
if pid < 1:
raise ValueError(u"SCHED_RR: PID must be higher then 1.")
if 1 <= priority <= 99:
cmd = f"chrt -r -p {priority} {pid}"
ret, _, _ = ssh.exec_command_sudo(cmd)
if ret != 0:
raise RuntimeError(
f"SCHED_RR: Failed to set policy for PID {pid}."
)
else:
raise ValueError(u"SCHED_RR: Priority must be in range 1-99.")
@staticmethod
def set_proc_scheduling_other(node, pid):
"""Set normal scheduling of a process to SCHED_OTHER for specified PID.
:param node: Node where to apply scheduling changes.
:param pid: Process ID.
:type node: dict
:type pid: int
:raises ValueError: Parameters out of allowed ranges.
:raises RuntimeError: Failed to set policy for PID.
"""
ssh = SSH()
ssh.connect(node)
if pid < 1:
raise ValueError(u"SCHED_OTHER: PID must be higher then 1.")
cmd = f"chrt -o -p 0 {pid}"
ret, _, _ = ssh.exec_command_sudo(cmd)
if ret != 0:
raise RuntimeError(
f"SCHED_OTHER: Failed to set policy for PID {pid}."
)
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