linux tc

Linux TC 命令

Traffic Control 流量控制

Posted by LXG on November 7, 2019

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Linux TC-gitub

概念

TC 是 Traffic Control 的缩写。在Linux中，流量控制是通过建立数据包队列(Queue)，并控制各个队列中数据包的发送方式实现的

基本工作原理

linux_tc

  • 接收包从输入接口 (Input Interface) 进来后，将经过输入流量限制 (Ingress Policing) 以丢弃不符合规定的数据包。而符合规定的数据包则交给输入多路选择器材 (Input De-Multiplexing) 进行判断选择

  • 输入多路选择器的选择结果是，如果数据包的目地是本机，则将该包送给上层处理，否则需要将数据交到转发块 (Forwarding Blcok) 去处理。转发块同时也接收来自本机上层 (TCP\UDP) 产生的数据包

  • 转发块通过查看路由表，决定处理包的下一个目的地。然后，转发块对数据包进行排列整合以便将它们送到对应的输出接口 (Output Interface)

具体实现

系统会建立许多队列及对应的队列规则 (queuing disipline, 简称qdisc)

  • 针对网络物理设备（如以太网卡eth0）绑定一个队列qdisc

  • 在该队列上建立class

  • 为每一个分类建立一个基于路由的过滤器filter

  • 最后与过滤器配合，建立特定的路由表

无分类的队列规则（Classless qdisc）

该规则对进入网卡的数据包不加区分，统一对待。使用这种规定的处理能否对数据包重新编排、延迟或丢弃。这种类型是针对整个网卡的流量进行调整。

常用的qdisc如下：

  • fifo(First In First Out, 先进先出队列)：最简单的控制

  • SFQ(Stochastic Fairness Queuing, 随机公平队列)：对发送会话进行重排，每个发送会话可以公平的发送数据

  • RED(Random Eraly Detection, 前向随机丢包)：用于模拟流量接近带宽限制时丢包的情况

  • TBF(Token Bucket Fliter, 令牌桶过滤器)：可较好地使得流量降低到预设值。适合高带宽的环境。这类qdisc使用的流量控制手段主要是排序、限速、丢包

InterfaceCmd

InterfaceCmd 用来管理和控制系统中的网络设备


system/netd

./server/RouteController.cpp
./server/BandwidthController.cpp
./server/ResolverController.cpp
./server/PPPOEController.cpp
./server/TetherController.cpp
./server/StrictController.cpp
./server/IPv6TetherController.cpp
./server/FirewallController.cpp
./server/PerfController.cpp
./server/NetworkController.cpp
./server/PppController.cpp
./server/IdletimerController.cpp
./server/ClatdController.cpp
./server/SoftapController.cpp
./server/ThrottleController.cpp
./server/InterfaceController.cpp
./server/BridgeController.cpp
./server/Controllers.cpp
./server/NatController.cpp

背景知识

虚拟网络设备

Linux虚拟网络-IBM

IFB设备

IFB (Intermediate Functional Block) 是 IMQ (Intermediate Queuing) 的替代者，二者都是Linux为更好地完成流量控制而实现的虚拟设备。

Linux 丰富的流量控制手段和规则都是针对出口流量的，即大多数排队规则（qdisc）都是用于输出方向的。而输入方向主要是入口流量控制只有一个规则，即ingress qdisc, 系统新增了一种方式，用于重定向incoming packets，通过ingress disc 把输入方向的数据包重定向到虚拟设备IFB，而IFB的输出方向配置多种qdisc, 就可以达到对输入方向的流量做队列调度的目的

linux_tc_ifb

网络设备编程

Netdevice是Linux平台中直接针对底层网络设备编程的一套接口，其使用方法很简单，就是利用socket句柄和ioctl函数来操作指定的网络设备

system/core/libnetutils/ifc_utils.c


static void ifc_init_ifr(const char *name, struct ifreq *ifr)
{
    memset(ifr, 0, sizeof(struct ifreq));
    strncpy(ifr->ifr_name, name, IFNAMSIZ);
    ifr->ifr_name[IFNAMSIZ - 1] = 0;
}

static int ifc_set_flags(const char *name, unsigned set, unsigned clr)
{
    struct ifreq ifr;
    ifc_init_ifr(name, &ifr);

    if(ioctl(ifc_ctl_sock, SIOCGIFFLAGS, &ifr) < 0) return -1;
    ifr.ifr_flags = (ifr.ifr_flags & (~clr)) | set;
    return ioctl(ifc_ctl_sock, SIOCSIFFLAGS, &ifr);
}

int ifc_up(const char *name)
{
    int ret = ifc_set_flags(name, IFF_UP, 0);
    if (DBG) printerr("ifc_up(%s) = %d", name, ret);
    return ret;
}

int ifc_down(const char *name)
{
    int ret = ifc_set_flags(name, 0, IFF_UP);
    if (DBG) printerr("ifc_down(%s) = %d", name, ret);
    return ret;
}

代码

system/netd/server/ThrottleController.cpp


#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>

#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>

#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/pkt_sched.h>

#define LOG_TAG "ThrottleController"
#include <cutils/log.h>
#include <netutils/ifc.h>

#include "ThrottleController.h"
#include "NetdConstants.h"

extern "C" int ifc_init(void);
extern "C" int ifc_up(const char *name);
extern "C" int ifc_down(const char *name);

ThrottleController::ThrottleController(){
    mModemRx = -1;
    mModemTx = -1;
}
ThrottleController::~ThrottleController(){
}

int ThrottleController::runTcCmd(const char *cmd) {

    ALOGE("runTcCmd: %s", cmd);

    char *buffer;
    size_t len = strnlen(cmd, 255);
    int res;

    if (len == 255) {
        ALOGE("tc command too long");
        errno = E2BIG;
        return -1;
    }

    asprintf(&buffer, "%s %s", TC_PATH, cmd);
    res = system_nosh(buffer);
    free(buffer);
    return res;
}

int ThrottleController::setInterfaceThrottle(const char *iface, int rxKbps, int txKbps) {
    char cmd[512];
    char ifn[65];

    memset(ifn, 0, sizeof(ifn));
    strncpy(ifn, iface, sizeof(ifn)-1);

    if (txKbps == -1) {
        reset(ifn);
        return 0;
    }

    /*
     * by mtk80842, reset configuration before setting
     */
    reset(ifn);

    /*
     *
     * Target interface configuration
     *
     */

    /*
     * Add root qdisc for the interface
     */
    sprintf(cmd, "qdisc add dev %s root handle 1: htb default 1 r2q 1000", ifn);
    if (runTcCmd(cmd)) {
        ALOGE("Failed to add root qdisc (%s)", strerror(errno));
        goto fail;
    }

    /*
     * Add our egress throttling class
     */
    sprintf(cmd, "class add dev %s parent 1: classid 1:1 htb rate %dkbit", ifn, txKbps);
    if (runTcCmd(cmd)) {
        ALOGE("Failed to add egress throttling class (%s)", strerror(errno));
        goto fail;
    }

    if(rxKbps == -1){
        ALOGI("setInterfaceThrottle success but NO RX, ifn = %s", ifn);
        return 0;
    }

    /*
     * Bring up the IFD device
     */
    ifc_init();
    if (ifc_up("ifb0")) {
        ALOGE("Failed to up ifb0 (%s)", strerror(errno));
        goto fail;
    }

    /*
     * Add root qdisc for IFD
     */
    sprintf(cmd, "qdisc add dev ifb0 root handle 1: htb default 1 r2q 1000");
    if (runTcCmd(cmd)) {
        ALOGE("Failed to add root ifb qdisc (%s)", strerror(errno));
        goto fail;
    }

    /*
     * Add our ingress throttling class
     */
    sprintf(cmd, "class add dev ifb0 parent 1: classid 1:1 htb rate %dkbit", rxKbps);
    if (runTcCmd(cmd)) {
        ALOGE("Failed to add ingress throttling class (%s)", strerror(errno));
        goto fail;
    }

    /*
     * Add ingress qdisc for pkt redirection
     */
    sprintf(cmd, "qdisc add dev %s ingress", ifn);
    if (runTcCmd(cmd)) {
        ALOGE("Failed to add ingress qdisc (%s)", strerror(errno));
        goto fail;
    }

    /*
     * Add filter to link <ifn> -> ifb0
     */
    sprintf(cmd, "filter add dev %s parent ffff: protocol ip prio 10 u32 match "
            "u32 0 0 flowid 1:1 action mirred egress redirect dev ifb0", ifn);
    if (runTcCmd(cmd)) {
        ALOGE("Failed to add ifb filter (%s)", strerror(errno));
        goto fail;
    }

    ALOGI("setInterfaceThrottle success, ifn = %s", ifn);

    return 0;
fail:
    reset(ifn);
    return -1;
}

void ThrottleController::reset(const char *iface) {
    char cmd[128];

    ALOGI("reset %s qdisc", iface);

    sprintf(cmd, "qdisc del dev %s root", iface);
    runTcCmd(cmd);
    sprintf(cmd, "qdisc del dev %s ingress", iface);
    runTcCmd(cmd);

    runTcCmd("qdisc del dev ifb0 root");
}

int ThrottleController::getInterfaceRxThrottle(const char *iface, int *rx) {
    ALOGI("getInterfaceRxThrottle %s", iface);
    *rx = 0;
    return 0;
}

int ThrottleController::getInterfaceTxThrottle(const char *iface, int *tx) {
    ALOGI("getInterfaceTxThrottle %s", iface);
    *tx = 0;
    return 0;
}

int ThrottleController::getModemRxThrottle(int *rx) {
    *rx = mModemRx;
    return 0;
}

int ThrottleController::getModemTxThrottle(int *tx) {
    *tx = mModemTx;
    return 0;
}

int ThrottleController::setModemThrottle(int rxKbps, int txKbps) {
    unsigned int n = 0; unsigned int mask = 0;
    int idx = 0; unsigned int up = 0;
    // qcom: "rmnet_data0"
    const char* iface_list[] = {
      "ccmni0",
      "ccmni1",
      "ccmni2",
      0
    };

    mModemRx = rxKbps;
    mModemTx = txKbps;
    ifc_init();
    while(iface_list[idx] != 0){
        up = 0;
        ifc_is_up(iface_list[idx], &up);
        if(up == 1){
            n++;
            mask |= (1 << idx);
            ALOGD("%s is up, n = %d, mask = 0x%x", iface_list[idx], n, mask);
        }
        idx++;
    }
    ifc_close();
    if(n == 0){
        ALOGE("setModemThrottle: no modem interface is up !");
        return -1;
    }
    if(rxKbps >= 0)
        rxKbps = rxKbps/n;
    if(txKbps >= 0)
        txKbps = txKbps/n;

    idx = 0;
    while(iface_list[idx] != 0){
        if(mask & (1 << idx)){
            ALOGD("setModemThrottle for %s: rx %d, tx %d !",
            iface_list[idx], rxKbps, txKbps);
            setInterfaceThrottle(iface_list[idx], rxKbps, txKbps);
        }
        idx++;
    }

    return 0;
}

MTK 日志


11-07 18:07:24.613   446  1084 D FrameworkListener: dispatchCommand data = (103 interface setthrottle modem 80 160)
11-07 18:07:24.613   446  1084 D ThrottleController: ccmni1 is up, n = 1, mask = 0x2
11-07 18:07:24.613   446  1084 D ThrottleController: setModemThrottle for ccmni1: rx 80, tx 160 !
11-07 18:07:24.613   446  1084 I ThrottleController: reset ccmni1 qdisc
11-07 18:07:24.613   446  1084 E ThrottleController: runTcCmd: qdisc del dev ccmni1 root
11-07 18:07:24.651   446  1084 E ThrottleController: runTcCmd: qdisc del dev ccmni1 ingress
11-07 18:07:24.695   446  1084 E ThrottleController: runTcCmd: qdisc del dev ifb0 root
11-07 18:07:24.734   446  1084 E ThrottleController: runTcCmd: qdisc add dev ccmni1 root handle 1: htb default 1 r2q 1000
11-07 18:07:24.768   446  1084 E ThrottleController: runTcCmd: class add dev ccmni1 parent 1: classid 1:1 htb rate 160kbit
11-07 18:07:24.801   446  1084 D DHCP    : ifc_up(ifb0) = 0
11-07 18:07:24.801   446  1084 E ThrottleController: runTcCmd: qdisc add dev ifb0 root handle 1: htb default 1 r2q 1000
11-07 18:07:24.834   446  1084 E ThrottleController: runTcCmd: class add dev ifb0 parent 1: classid 1:1 htb rate 80kbit
11-07 18:07:24.868   446  1084 E ThrottleController: runTcCmd: qdisc add dev ccmni1 ingress
11-07 18:07:24.901   446  1084 E ThrottleController: runTcCmd: filter add dev ccmni1 parent ffff: protocol ip prio 10 u32 match u32 0 0 flowid 1:1 action mirred egress
redirect dev ifb0
11-07 18:07:24.934   446  1084 I ThrottleController: setInterfaceThrottle success, ifn = ccmni1

QCOM 日志


11-07 18:25:52.721   769  1538 D ThrottleController: rmnet_data0 is up, n = 1, mask = 0x1
11-07 18:25:52.721   769  1538 D ThrottleController: setModemThrottle for rmnet_data0: rx 80, tx 80 !
11-07 18:25:52.721   769  1538 I ThrottleController: reset rmnet_data0 qdisc
11-07 18:25:52.721   769  1538 E ThrottleController: runTcCmd: qdisc del dev rmnet_data0 root
11-07 18:25:52.802   769  1538 E ThrottleController: runTcCmd: qdisc del dev rmnet_data0 ingress
11-07 18:25:52.895   769  1538 E ThrottleController: runTcCmd: qdisc del dev ifb0 root
11-07 18:25:52.946   769  1538 E ThrottleController: runTcCmd: qdisc add dev rmnet_data0 root handle 1: htb default 1 r2q 1000
11-07 18:25:52.999   769  1538 E ThrottleController: runTcCmd: class add dev rmnet_data0 parent 1: classid 1:1 htb rate 80kbit
11-07 18:25:53.057   769  1538 E ThrottleController: runTcCmd: qdisc add dev ifb0 root handle 1: htb default 1 r2q 1000
11-07 18:25:53.109   769  1538 E ThrottleController: runTcCmd: class add dev ifb0 parent 1: classid 1:1 htb rate 80kbit

11-07 18:25:53.164   769  1538 E ThrottleController: runTcCmd: qdisc add dev rmnet_data0 ingress
11-07 18:25:53.228   769  1538 E ThrottleController: runTcCmd: filter add dev rmnet_data0 parent ffff: protocol ip prio 10 u32 match u32 0 0 flowid 1:1 action mirred egress redirect dev ifb0

// fail
11-07 18:25:53.317   769  1538 E ThrottleController: Failed to add ifb filter (No such device)
11-07 18:25:53.317   769  1538 I ThrottleController: reset rmnet_data0 qdisc
11-07 18:25:53.317   769  1538 E ThrottleController: runTcCmd: qdisc del dev rmnet_data0 root
11-07 18:25:53.375   769  1538 E ThrottleController: runTcCmd: qdisc del dev rmnet_data0 ingress
11-07 18:25:53.427   769  1538 E ThrottleController: runTcCmd: qdisc del dev ifb0 root
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