Re: [libvirt-users] Need to increase the rx and tx buffer size of my interface

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