Hi Yalan,Thank you for your response. I do not have the following packages installedvhost backend driverqemu-kvm-rhev packageAre 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 KurianOn Thu, Oct 26, 2017 at 6:45 AM, Yalan Zhang <yalzhang@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#elementsNICSEtherne t tx_queue_sizeThe 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-rhevlibvirt-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=32:33:3 -device virtio-net-pci,csum=off,gso=of4:35:36 f,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,v ectors=12,rx_queue_size=512,tx ,netdev=hostnet_queue_size=512 0,id=net0,mac=52:54:00:00:b5: 99,bus=pci.0,addr=0x3 3. check on guest# ethtool -g eth0Ring parameters for eth0:Pre-set maximums:RX: 512 ==> rx_queue_size worksRX Mini: 0RX Jumbo: 0TX: 256 ===> no changeCurrent hardware settings:RX: 512 ==> rx_queue_size worksRX Mini: 0RX Jumbo: 0TX: 256 ===> no change# ethtool -l eth0Channel parameters for eth0:Pre-set maximums:RX: 0TX: 0Other: 0Combined: 5 ==> queues what we setCurrent hardware settings:RX: 0TX: 0Other: 0Combined: 1If 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 rhel7Domain 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=of f,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_queu e_size=512,tx_queue_size=512 ,netdev=hostnet0,id=net0,mac= 52:54:00:00:b5:99,bus=pci.0,ad dr=0x3 "mq=on,vectors=12" is missing, indicates there is no multiqueueand check on guest# ethtool -l eth0Channel parameters for eth0:Pre-set maximums:RX: 0TX: 0Other: 0Combined: 1 ==> no multiqueueCurrent hardware settings:RX: 0TX: 0Other: 0Combined: 1# ethtool -g eth0Ring parameters for eth0:Pre-set maximums:RX: 512RX Mini: 0RX Jumbo: 0TX: 256Current hardware settings:RX: 512RX Mini: 0RX Jumbo: 0TX: 256
-------
Best Regards,
Yalan Zhang
IRC: yalzhang
Internal phone: 8389413On Thu, Oct 26, 2017 at 2:33 AM, Ashish Kurian <ashishbnv@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 KurianOn Wed, Oct 25, 2017 at 5:07 PM, Ashish Kurian <ashishbnv@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 interleaveElement domain failed to validate contentWhat 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 logBest Regards,
Ashish KurianOn Wed, Oct 25, 2017 at 2:50 PM, Michal Privoznik <mprivozn@redhat.com> wrote:So what does the qemu command line look like? You can find it in eitherOn 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'/>
libvirtd log or domain log.
http://wiki.libvirt.org/page/DebugLogs
Michal
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