Description of problem:


Version-Release number of selected component (if applicable):
[root@netqe27 ~]# uname -r
4.18.0-305.25.1.el8_4.x86_64
[root@netqe27 ~]# rpm -qa|grep dpdk
dpdk-20.11-3.el8.x86_64
dpdk-tools-20.11-3.el8.x86_64


How reproducible:


Steps to Reproduce:
Run testpmd as switch case
1. start testpmd
/usr/bin/dpdk-testpmd -l 38,18,36 -n 4 --socket-mem 1024,1024 --vdev net_vhost0,iface=/tmp/vhost0,client=1,iommu-support=1,queues=1 --vdev net_vhost1,iface=/tmp/vhost1,client=1,iommu-support=1,queues=1 -- -i --nb-cores=2 --txq=1 --rxq=1 --forward-mode=io

2.start guest
<domain type='kvm'>
  <name>g1</name>
  <memory unit='KiB'>8388608</memory>
  <currentMemory unit='KiB'>8388608</currentMemory>
  <memoryBacking>
    <hugepages>
      <page size='1048576' unit='KiB'/>
    </hugepages>
    <locked/>
    <access mode='shared'/>
  </memoryBacking>
  <vcpu placement='static'>3</vcpu>
  <cputune>
    <vcpupin vcpu='0' cpuset='2'/>
    <vcpupin vcpu='1' cpuset='22'/>
    <vcpupin vcpu='2' cpuset='4'/>
    <emulatorpin cpuset='0,20'/>
  </cputune>
  <numatune>
    <memory mode='strict' nodeset='0'/>
  </numatune>
  <resource>
    <partition>/machine</partition>
  </resource>
  <os>
    <type arch='x86_64' machine='q35'>hvm</type>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pmu state='off'/>
    <vmport state='off'/>
    <ioapic driver='qemu'/>
  </features>
  <cpu mode='host-passthrough' check='none'>
    <feature policy='require' name='tsc-deadline'/>
    <numa>
      <cell id='0' cpus='0-2' memory='8388608' unit='KiB' memAccess='shared'/>
    </numa>
  </cpu>
  <clock offset='utc'>
    <timer name='rtc' tickpolicy='catchup'/>
    <timer name='pit' tickpolicy='delay'/>
    <timer name='hpet' present='no'/>
  </clock>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <pm>
    <suspend-to-mem enabled='no'/>
    <suspend-to-disk enabled='no'/>
  </pm>
  <devices>
    <emulator>/usr/libexec/qemu-kvm</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/var/lib/libvirt/images/g1.qcow2'/>
      <backingStore/>
      <target dev='vda' bus='virtio'/>
      <alias name='virtio-disk0'/>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
    </disk>
    <controller type='usb' index='0' model='none'>
      <alias name='usb'/>
    </controller>
    <controller type='pci' index='0' model='pcie-root'>
      <alias name='pcie.0'/>
    </controller>
    <controller type='pci' index='1' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='1' port='0x10'/>
      <alias name='pci.1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </controller>
    <controller type='pci' index='2' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='2' port='0x11'/>
      <alias name='pci.2'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </controller>
    <controller type='pci' index='3' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='3' port='0x8'/>
      <alias name='pci.3'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </controller>
    <controller type='pci' index='4' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='4' port='0x9'/>
      <alias name='pci.4'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </controller>
    <controller type='pci' index='5' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='5' port='0xa'/>
      <alias name='pci.5'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </controller>
    <controller type='pci' index='6' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='6' port='0xb'/>
      <alias name='pci.6'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
    </controller>
    <controller type='sata' index='0'>
      <alias name='ide'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
    </controller>
    <interface type='bridge'>
      <mac address='52:54:00:01:02:03'/>
      <source bridge='virbr0'/>
      <model type='virtio'/>
    </interface>
    <interface type='vhostuser'>
      <mac address='00:de:ad:00:00:01'/>
      <source type='unix' path='/tmp/vhost0' mode='server'/>
      <model type='virtio'/>
      <driver name='vhost' rx_queue_size='1024' tx_queue_size='1024' iommu='on' ats='on'>
  <host mrg_rxbuf='off'/>
  </driver>
      <address type='pci' domain='0x0000' bus='0x3' slot='0x00' function='0x0'/>
    </interface>
    <interface type='vhostuser'>
      <mac address='00:de:ad:00:00:02'/>
      <source type='unix' path='/tmp/vhost1' mode='server'/>
      <model type='virtio'/>
      <driver name='vhost' rx_queue_size='1024' tx_queue_size='1024' iommu='on' ats='on'>
  <host mrg_rxbuf='off'/>
  </driver>
      <address type='pci' domain='0x0000' bus='0x4' slot='0x00' function='0x0'/>
    </interface>
    <serial type='pty'>
      <source path='/dev/pts/1'/>
      <target type='isa-serial' port='0'>
        <model name='isa-serial'/>
      </target>
      <alias name='serial0'/>
    </serial>
    <console type='pty' tty='/dev/pts/1'>
      <source path='/dev/pts/1'/>
      <target type='serial' port='0'/>
      <alias name='serial0'/>
    </console>
    <input type='mouse' bus='ps2'>
      <alias name='input0'/>
    </input>
    <input type='keyboard' bus='ps2'>
      <alias name='input1'/>
    </input>
    <graphics type='vnc' port='5900' autoport='yes' listen='0.0.0.0'>
      <listen type='address' address='0.0.0.0'/>
    </graphics>
    <video>
      <model type='cirrus' vram='16384' heads='1' primary='yes'/>
      <alias name='video0'/>
      <address type='pci' domain='0x0000' bus='0x05' slot='0x00' function='0x0'/>
    </video>
    <memballoon model='virtio'>
      <alias name='balloon0'/>
      <address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/>
    </memballoon>
    <iommu model='intel'>
      <driver intremap='on' caching_mode='on' iotlb='on'/>
    </iommu>
  </devices>
  <seclabel type='dynamic' model='selinux' relabel='yes'/>
</domain>
3. start testpmd ininside guest
dpdk-testpmd -l 0-2 -n 1 --socket-mem 1024 -- -i --forward-mode=io --burst=32 --rxd=8192 --txd=8192 --max-pkt-len=9600 --mbuf-size=9728 --nb-cores=2 --rxq=1 --txq=1 --mbcache=512  --auto-start

Actual results:
It got about very low performance(smaller than 1mpps), such as 0.6mpps

Expected results:
It should be got higher performance, such as 8mpps.

Additional info:
[root@netqe27 ~]# lspci|grep "ConnectX-6 Lx"
04:00.0 Ethernet controller: Mellanox Technologies MT2894 Family [ConnectX-6 Lx]
04:00.1 Ethernet controller: Mellanox Technologies MT2894 Family [ConnectX-6 Lx]

https://beaker.engineering.redhat.com/jobs/7351790
https://beaker.engineering.redhat.com/jobs/7355546