Linux多队列网卡的硬件的实现详解

6.多队列网卡识别

#lspci -vvv

Ethernet controller的条目内容，如果有MSI-X && Enable+ && TabSize > 1，则该网卡是多队列网卡，如图4.4所示。

图4.4 lspci内容

Message Signaled Interrupts(MSI)是PCI规范的一个实现，可以突破CPU 256条interrupt的限制，使每个设备具有多个中断线变成可能，多队列网卡驱动给每个queue申请了MSI。MSI-X是MSI数组，Enable+指使能，TabSize是数组大小。

# setting up irq affinity according to /proc/interrupts

# 2008-11-25 Robert Olsson

# 2009-02-19 updated by Jesse Brandeburg

#

# > Dave Miller:

# (To get consistent naming in /proc/interrups)

# I would suggest that people use something like:

# char buf[IFNAMSIZ+6];

#

# sprintf(buf, "%s-%s-%d",

#         netdev->name,

#  (RX_INTERRUPT ? "rx" : "tx"),

#  queue->index);

#

#  Assuming a device with two RX and TX queues.

#  This script will assign: 

#

# eth0-rx-0  CPU0

# eth0-rx-1  CPU1

# eth0-tx-0  CPU0

# eth0-tx-1  CPU1

#

set_affinity()

{

    MASK=$((1<<$VEC))

    printf "%s mask=%X for /proc/irq/%d/smp_affinity\n" $DEV $MASK $IRQ

    printf "%X" $MASK > /proc/irq/$IRQ/smp_affinity

    #echo $DEV mask=$MASK for /proc/irq/$IRQ/smp_affinity

    #echo $MASK > /proc/irq/$IRQ/smp_affinity

}

if [ "$1" = "" ] ; then

 echo "Description:"

 echo "    This script attempts to bind each queue of a multi-queue NIC"

 echo "    to the same numbered core, ie tx0|rx0 --> cpu0, tx1|rx1 --> cpu1"

 echo "usage:"

 echo "    $0 eth0 [eth1 eth2 eth3]"

fi

# check for irqbalance running

IRQBALANCE_ON=`ps ax | grep -v grep | grep -q irqbalance; echo $?`

if [ "$IRQBALANCE_ON" == "0" ] ; then

 echo " WARNING: irqbalance is running and will"

 echo "          likely override this script's affinitization."

 echo "          Please stop the irqbalance service and/or execute"

 echo "          'killall irqbalance'"

fi

#

# Set up the desired devices.

#

for DEV in $*

do

  for DIR in rx tx TxRx

  do

     MAX=`grep $DEV-$DIR /proc/interrupts | wc -l`

     if [ "$MAX" == "0" ] ; then

       MAX=`egrep -i "$DEV:.*$DIR" /proc/interrupts | wc -l`

     fi

     if [ "$MAX" == "0" ] ; then

       echo no $DIR vectors found on $DEV

       continue

       #exit 1

     fi

     for VEC in `seq 0 1 $MAX`

     do

        IRQ=`cat /proc/interrupts | grep -i $DEV-$DIR-$VEC"$"  | cut  -d:  -f1 | sed "s/ //g"`

        if [ -n  "$IRQ" ]; then

          set_affinity

        else

           IRQ=`cat /proc/interrupts | egrep -i $DEV:v$VEC-$DIR"$"  | cut  -d:  -f1 | sed "s/ //g"`

           if [ -n  "$IRQ" ]; then

             set_affinity

           fi

        fi

     done

  done

done

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