Router latency tuner

router_latency.py

#!/usr/bin/env python3
import argparse
import time
import logging
import psutil

FILENAME_FORMAT = "/sys/devices/system/cpu/cpu{0:d}/power/pm_qos_resume_latency_us"


logger = logging.getLogger(__name__)



class IFaceStats:

    __slots__ = ('name', 'r_packets', 't_packets')

    def __init__(self, name):
        self.name = name
        self.r_packets = None
        self.t_packets = None


def set_latency(val):
    ok = True
    for i in range(psutil.cpu_count()):
        filename = FILENAME_FORMAT.format(i)
        try:
            with open(filename, "w") as f:
                f.write(str(val))
        except OSError:
            logger.exception("Can't set latency for cpu: {0:d}".format(i))
            ok = False

    return ok


def start(ifaces, interval=10, alpha=0.3, rate=140):
    ifaces = frozenset(ifaces)
    state = {}

    if alpha > 1 or alpha <= 0:
        raise ValueError("Alpha can't be higher than 1")

    set_latency(0)  # validate that we can change this setting

    rev_alpha = 1.0 - alpha
    low_latency_threshold = rate * interval
    powersave_threshold = low_latency_threshold * 0.7

    for ifname, ifstats in psutil.net_io_counters(pernic=True).items():
        if ifname not in ifaces:
            continue

        obj = IFaceStats(ifname)
        obj.r_packets = ifstats.packets_recv
        obj.t_packets = ifstats.packets_sent
        state[ifname] = obj

    if not state:
        raise ValueError("No matched interfaces")

    exp_counter = 0.0
    low_latency = False


    try:
        while True:
            total_diff = 0
            time.sleep(interval)

            for ifname, ifstats in psutil.net_io_counters(pernic=True).items():
                if ifname not in ifaces:
                    continue

                if_state = state[ifname]

                r_diff = ifstats.packets_recv - if_state.r_packets
                t_diff = ifstats.packets_sent - if_state.t_packets

                if_state.r_packets = ifstats.packets_recv
                if_state.t_packets = ifstats.packets_sent

                total_diff += r_diff + t_diff

            exp_counter = exp_counter * rev_alpha + total_diff * alpha

            if exp_counter > low_latency_threshold and not low_latency:
                set_latency(100)
                low_latency = True
                # print("set low latency")
            elif exp_counter < powersave_threshold and low_latency:
                set_latency(0)
                low_latency = False
                # print("set power saving")

    except KeyboardInterrupt:
        print("Quit")
    finally:
        set_latency(0)


def main(args=None):
    parser = argparse.ArgumentParser(description="Set system C states (for latency)")
    parser.add_argument('-i', '--interface', type=str, required=True,
                        action='append', help='Interface for stats')
    parser.add_argument('-t', '--interval', type=float, default=10)
    parser.add_argument('-r', '--rate', type=int, default=140)
    parser.add_argument('--alpha', type=float, default=0.3)
    params = parser.parse_args(args=args)

    start(params.interface, interval=params.interval, rate=params.rate,
          alpha=params.alpha)


if __name__ == '__main__':
    main()

router_latency.service

[Unit]
Description=Set Router latency to optimize power consumption
After=network.target

[Service]
Type=simple
User=root
Group=root
ProtectKernelModules=yes
ExecStart=/usr/local/bin/router_latency.py -i eth1 -i home -t 10 -r 132 --alpha 0.35
Restart=always
KillSignal=SIGINT
StandardInput=null
StandardOutput=syslog
StandardError=syslog
CapabilityBoundingSet=~CAP_SYS_PTRACE
SystemCallFilter=~@debug @keyring @module @mount @chown @cpu-emulation
PrivateTmp=yes
ProtectHome=yes
ProtectSystem=strict
PrivateDevices=yes
NoNewPrivileges=yes
LimitNPROC=45
TasksMax=10
Nice=19
ProtectKernelTunables=no
InaccessiblePaths=/boot /mnt /media /opt /var
ReadOnlyPaths=/proc
#SELinuxContext=system_u:system_r:router_latency_t

[Install]
WantedBy=multi-user.target