[libvirt-users] Need to increase the rx and tx buffer size of my interface
Yalan Zhang
yalzhang at redhat.com
Thu Oct 26 06:22:44 UTC 2017
Hi Ashish,
Are these packages available for free? How can I install them?
=> You did have vhost backend driver. Do not set <driver name='qemu'...>,
by default it will use vhost as backend driver.
Is it possible to have my interfaces with an IP address inside the VM to
be bridged to the physical interfaces on the host?
=> Yes, you can create a linux bridge with physical interface connected,
and use bridge type interface. Refer to https://libvirt.org/
formatdomain.html#elementsNICSBridge
direct type is also ok (but your host and guest have no access to each
other).
Is it also a possibility that I change the rx and tx buffer on the physical
interface on the host and it is reflected automatically inside the VM as
you said it will always receive the default value of the host?
=> No, it do not receive the default value of the host. It's the default
value related with the virtual device driver on the guest.
hostdev type interface will passthrough the physical interface or VF of the
host to guest, it will get the device's parameters for rx and tx buffer.
-------
Best Regards,
Yalan Zhang
IRC: yalzhang
Internal phone: 8389413
On Thu, Oct 26, 2017 at 1:30 PM, Ashish Kurian <ashishbnv at gmail.com> wrote:
> Hi Yalan,
>
> Thank you for your response. I do not have the following packages installed
>
> vhost backend driver
> qemu-kvm-rhev package
>
> Are these packages available for free? How can I install them?
>
> In my KVM VM, I must have an IP address to the interfaces that I am trying
> to increasing the buffers. That is the reason I was using macvtap (direct
> type interface). Is it possible to have my interfaces with an IP address
> inside the VM to be bridged to the physical interfaces on the host?
>
> Is it also a possibility that I change the rx and tx buffer on the
> physical interface on the host and it is reflected automatically inside the
> VM as you said it will always receive the default value of the host?
>
>
> Best Regards,
> Ashish Kurian
>
> On Thu, Oct 26, 2017 at 6:45 AM, Yalan Zhang <yalzhang at redhat.com> wrote:
>
>> Hi Ashish,
>>
>> I have tested with your xml in the first mail, and it works for rx_queue_size(see
>> below).
>> multiqueue need to work with vhost backend driver. And when you set
>> "queues=1" it will ignored.
>>
>> Please check your qemu-kvm-rhev package, should be newer than
>> qemu-kvm-rhev-2.9.0-16.el7_4.2
>> And the logs?
>>
>> tx_queue_size='512' will not work in the guest with direct type
>> interface, in fact, no matter what you set, it will not work and guest will
>> get the default '256'.
>> We only support vhost-user backend to have more than 256. refer to
>> https://libvirt.org/formatdomain.html#elementsNICSEthernet
>>
>> tx_queue_size
>> The optional tx_queue_size attribute controls the size of virtio ring
>> for each queue as described above. The default value is hypervisor
>> dependent and may change across its releases. Moreover, some hypervisors
>> may pose some restrictions on actual value. For instance, QEMU v2.9
>> requires value to be a power of two from [256, 1024] range. In addition to
>> that, this may work only for a subset of interface types, e.g.
>> aforementioned QEMU enables this option only for vhostuser type. Since
>> 3.7.0 (QEMU and KVM only)
>> multiqueue only supports vhost as backend driver.
>>
>> # rpm -q libvirt qemu-kvm-rhev
>> libvirt-3.2.0-14.el7_4.3.x86_64
>> qemu-kvm-rhev-2.9.0-16.el7_4.9.x86_64
>>
>> 1. the xml as below
>> <interface type='direct'>
>> <mac address='52:54:00:00:b5:99'/>
>> <source dev='eno1' mode='vepa'/>
>> <model type='virtio'/>
>> <driver name='vhost' queues='5' rx_queue_size='512'
>> tx_queue_size='512'>
>> <host csum='off' gso='off' tso4='off' tso6='off' ecn='off'
>> ufo='off' mrg_rxbuf='off'/>
>> <guest csum='off' tso4='off' tso6='off' ecn='off' ufo='off'/>
>> </driver>
>> <address type='pci' domain='0x0000' bus='0x00' slot='0x03'
>> function='0x0'/>
>> </interface>
>>
>> 2. after start the vm, check the qemu command line:
>> *-netdev
>> tap,fds=26:28:29:30:31,id=hostnet0,vhost=on,vhostfds=32:33:34:35:36*
>> -device virtio-net-pci,csum=off,gso=off,host_tso4=off,host_tso6=off,
>> host_ecn=off,host_ufo=off,mrg_rxbuf=off,guest_csum=off,guest
>> _tso4=off,guest_tso6=off,guest_ecn=off,guest_ufo=off,
>> *mq=on,vectors=12,rx_queue_size=512,tx_queue_size=512*,netdev=hostnet
>> 0,id=net0,mac=52:54:00:00:b5:99,bus=pci.0,addr=0x3
>>
>> 3. check on guest
>> # ethtool -g eth0
>> Ring parameters for eth0:
>> Pre-set maximums:
>> RX: *512 ==> rx_queue_size works*
>> RX Mini: 0
>> RX Jumbo: 0
>> TX: *256 ===> no change*
>> Current hardware settings:
>> RX: *512 **==> rx_queue_size works*
>> RX Mini: 0
>> RX Jumbo: 0
>> TX: *256 ===> no change*
>>
>> # ethtool -l eth0
>> Channel parameters for eth0:
>> Pre-set maximums:
>> RX: 0
>> TX: 0
>> Other: 0
>> Combined: *5 ==> queues what we set*
>> Current hardware settings:
>> RX: 0
>> TX: 0
>> Other: 0
>> Combined: 1
>>
>>
>> If change to qemu as driver,
>> # virsh edit rhel7
>> ..
>> <interface type='direct'>
>> <mac address='52:54:00:00:b5:99'/>
>> <source dev='eno1' mode='vepa'/>
>> <model type='virtio'/>
>> <driver name='qemu' queues='5' rx_queue_size='512'
>> tx_queue_size='512'>
>> <host csum='off' gso='off' tso4='off' tso6='off' ecn='off'
>> ufo='off' mrg_rxbuf='off'/>
>> <guest csum='off' tso4='off' tso6='off' ecn='off' ufo='off'/>
>> </driver>
>> <address type='pci' domain='0x0000' bus='0x00' slot='0x03'
>> function='0x0'/>
>> </interface>
>> ..
>> Domain rhel7 XML configuration edited. ==> the xml can validate and save
>>
>> # virsh start rhel7
>> Domain rhel7 started
>>
>>
>> # virsh dumpxml rhel7 | grep /interface -B9
>> <source dev='eno1' mode='vepa'/>
>> <target dev='macvtap0'/>
>> <model type='virtio'/>
>> *<driver name='qemu' queues='5' rx_queue_size='512'
>> tx_queue_size='512'>*
>> <host csum='off' gso='off' tso4='off' tso6='off' ecn='off'
>> ufo='off' mrg_rxbuf='off'/>
>> <guest csum='off' tso4='off' tso6='off' ecn='off' ufo='off'/>
>> </driver>
>> <alias name='net0'/>
>> <address type='pci' domain='0x0000' bus='0x00' slot='0x03'
>> function='0x0'/>
>> </interface>
>>
>>
>> * -netdev tap,fds=26:28:29:30:31*,id=hostnet0 -device
>> virtio-net-pci,csum=off,gso=off,host_tso4=off,host_tso6=off,
>> host_ecn=off,host_ufo=off,mrg_rxbuf=off,guest_csum=off,guest
>> _tso4=off,guest_tso6=off,guest_ecn=off,guest_ufo=off,
>> *rx_queue_size=512,tx_queue_size=512*,netdev=hostnet0,id=net0,mac=
>> 52:54:00:00:b5:99,bus=pci.0,addr=0x3
>>
>> *"mq=on,vectors=12" is missing*, indicates there is no multiqueue
>>
>> and check on guest
>>
>> # ethtool -l eth0
>> Channel parameters for eth0:
>> Pre-set maximums:
>> RX: 0
>> TX: 0
>> Other: 0
>> Combined: 1 ==> no multiqueue
>> Current hardware settings:
>> RX: 0
>> TX: 0
>> Other: 0
>> Combined: 1
>>
>> # ethtool -g eth0
>> Ring parameters for eth0:
>> Pre-set maximums:
>> RX: *512*
>> RX Mini: 0
>> RX Jumbo: 0
>> TX: 256
>> Current hardware settings:
>> RX: *512*
>> RX Mini: 0
>> RX Jumbo: 0
>> TX: 256
>>
>>
>>
>>
>> -------
>> Best Regards,
>> Yalan Zhang
>> IRC: yalzhang
>> Internal phone: 8389413
>>
>> On Thu, Oct 26, 2017 at 2:33 AM, Ashish Kurian <ashishbnv at gmail.com>
>> wrote:
>>
>>> Hi Michal,
>>>
>>> An update to what I have already said : when I try adding <driver
>>> name='qemu' txmode='iothread' ioeventfd='on' event_idx='off' queues='1'
>>> rx_queue_size='512' tx_queue_size='512'> although it showed me the error as
>>> mentioned, when I checked the xml again I saw that <driver name='qemu'
>>> txmode='iothread' ioeventfd='on' event_idx='off' > is added to the
>>> interface.
>>>
>>> The missing parameters are : queues='1' rx_queue_size='512'
>>> tx_queue_size='512'
>>>
>>> Best Regards,
>>> Ashish Kurian
>>>
>>> On Wed, Oct 25, 2017 at 5:07 PM, Ashish Kurian <ashishbnv at gmail.com>
>>> wrote:
>>>
>>>> Hi Michal,
>>>>
>>>> What I found was that when I restarted the machine and did a virsh edit
>>>> command to see the xml config, I see that it is was not actually changed.
>>>> This suggests why I saw 256 again after restarting.
>>>>
>>>> So now I tried again to edit the xml via virsh edit command and used
>>>> the following to set the parameters.
>>>>
>>>> <driver name='qemu' txmode='iothread' ioeventfd='on' event_idx='off'
>>>> queues='1' rx_queue_size='512' tx_queue_size='512'>
>>>> </driver>
>>>>
>>>> It was not accepted and I got the error saying :
>>>>
>>>>
>>>> error: XML document failed to validate against schema: Unable to
>>>> validate doc against /usr/share/libvirt/schemas/domain.rng
>>>> Extra element devices in interleave
>>>> Element domain failed to validate content
>>>>
>>>> What does this imply? I have two more other interfaces and do I have to
>>>> the same to them also?
>>>>
>>>> Btw, there are now logs generated now in the domain log or libvirtd log
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Best Regards,
>>>> Ashish Kurian
>>>>
>>>> On Wed, Oct 25, 2017 at 2:50 PM, Michal Privoznik <mprivozn at redhat.com>
>>>> wrote:
>>>>
>>>>> On 10/25/2017 01:53 PM, Ashish Kurian wrote:
>>>>> > Dear Users/Developers,
>>>>> >
>>>>> > I am using a KVM Ubuntu VM as a degrader to apply specific delays to
>>>>> > incoming packets. As the delay for my packets can be higher than 7.5
>>>>> > seconds, there is not enough buffer on my interface to buffer all the
>>>>> > packets. Therefore those overflowing packets are dropped in the
>>>>> machine and
>>>>> > not forwarded.
>>>>> >
>>>>> > When I tried to use the command ethtool -G ens8 rx 512 to increase
>>>>> the
>>>>> > buffer size, I get the following error.
>>>>> >
>>>>> > Cannot set device ring parameters: Operation not permitted
>>>>> >
>>>>> > I have kept the VM xml files as specified in the link :
>>>>> > https://libvirt.org/formatdomain.html. The value that I kept in my
>>>>> xml file
>>>>> > is as follows.
>>>>> >
>>>>> > <interface type='direct'>
>>>>> > <mac address='52:54:00:72:f9:eb'/>
>>>>> > <source dev='enp7s0f0' mode='vepa'/>
>>>>> > <model type='virtio'/>
>>>>> > <driver name='vhost' queues='5' rx_queue_size='512'
>>>>> > tx_queue_size='512'>
>>>>> > <host csum='off' gso='off' tso4='off' tso6='off' ecn='off'
>>>>> ufo='off'
>>>>> > mrg_rxbuf='off'/>
>>>>> > <guest csum='off' tso4='off' tso6='off' ecn='off' ufo='off'/>
>>>>> > </driver>
>>>>> > <address type='pci' domain='0x0000' bus='0x00' slot='0x08'
>>>>> > function='0x0'/>
>>>>> > </interface>
>>>>> > <interface type='direct'>
>>>>> > <mac address='52:54:00:00:b5:99'/>
>>>>> > <source dev='enp7s0f1' mode='vepa'/>
>>>>> > <model type='virtio'/>
>>>>> > <driver name='vhost' queues='5' rx_queue_size='512'
>>>>> > tx_queue_size='512'>
>>>>> > <host csum='off' gso='off' tso4='off' tso6='off' ecn='off'
>>>>> ufo='off'
>>>>> > mrg_rxbuf='off'/>
>>>>> > <guest csum='off' tso4='off' tso6='off' ecn='off' ufo='off'/>
>>>>> > </driver>
>>>>> > <address type='pci' domain='0x0000' bus='0x00' slot='0x09'
>>>>> > function='0x0'/>
>>>>>
>>>>> So what does the qemu command line look like? You can find it in either
>>>>> libvirtd log or domain log.
>>>>>
>>>>> http://wiki.libvirt.org/page/DebugLogs
>>>>>
>>>>> Michal
>>>>>
>>>>
>>>>
>>>
>>> _______________________________________________
>>> libvirt-users mailing list
>>> libvirt-users at redhat.com
>>> https://www.redhat.com/mailman/listinfo/libvirt-users
>>>
>>
>>
>
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