Hi Satish, Actually, the guess interface is not using tap anymore. <interface type='vhostuser'> <mac address='fa:16:3e:76:77:dd'/> <source type='unix' path='/var/run/openvswitch/vhu3766ee8a-86' mode='server'/> <target dev='vhu3766ee8a-86'/> <model type='virtio'/> <alias name='net0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface> It's totally bypass the kernel stack ? On Fri, Sep 8, 2023 at 5:02 AM Satish Patel <satish.txt@gmail.com> wrote:
I did test OVS-DPDK and it helps offload the packet process on compute nodes, But what about VMs it will still use a tap interface to attach from compute to vm and bottleneck will be in vm. I strongly believe that we have to run DPDK based guest to pass through the kernel stack.
I love to hear from other people if I am missing something here.
On Thu, Sep 7, 2023 at 5:27 PM Ha Noi <hanoi952022@gmail.com> wrote:
Oh. I heard from someone on the reddit said that Ovs-dpdk is transparent with user?
So It’s not correct?
On Thu, 7 Sep 2023 at 22:13 Satish Patel <satish.txt@gmail.com> wrote:
Because DPDK required DPDK support inside guest VM. It's not suitable for general purpose workload. You need your guest VM network to support DPDK to get 100% throughput.
On Thu, Sep 7, 2023 at 8:06 AM Ha Noi <hanoi952022@gmail.com> wrote:
Hi Satish,
Why dont you use DPDK?
Thanks
On Thu, 7 Sep 2023 at 19:03 Satish Patel <satish.txt@gmail.com> wrote:
I totally agreed with Sean on all his points but trust me, I have tried everything possible to tune OS, Network stack, multi-queue, NUMA, CPU pinning and name it.. but I didn't get any significant improvement. You may gain 2 to 5% gain with all those tweek. I am running the entire workload on sriov and life is happy except no LACP bonding.
I am very interesting is this project https://docs.openvswitch.org/en/latest/intro/install/afxdp/
On Thu, Sep 7, 2023 at 6:07 AM Ha Noi <hanoi952022@gmail.com> wrote:
Dear Smoney,
On Thu, Sep 7, 2023 at 12:41 AM <smooney@redhat.com> wrote:
> On Wed, 2023-09-06 at 11:43 -0400, Satish Patel wrote: > > Damn! We have noticed the same issue around 40k to 55k PPS. Trust > me > > nothing is wrong in your config. This is just a limitation of the > software > > stack and kernel itself. > its partly determined by your cpu frequency. > kernel ovs of yesteryear could handel about 1mpps total on a ~4GHZ > cpu. with per port troughpuyt being lower dependin on what > qos/firewall > rules that were apllied. > >
My CPU frequency is 3Ghz and using CPU Intel Gold 2nd generation. I think the problem is tuning in the compute node inside. But I cannot find any guide or best practices for it.
> moving form iptables firewall to ovs firewall can help to some degree > but your partly trading connection setup time for statead state > troughput > with the overhead of the connection tracker in ovs. > > using stateless security groups can help > > we also recently fixed a regression cause by changes in newer > versions of ovs. > this was notable in goign form rhel 8 to rhel 9 where litrally it > reduced > small packet performce to 1/10th and jumboframes to about 1/2 > on master we have a config option that will set the default qos on a > port to linux-noop > > https://github.com/openstack/os-vif/blob/master/vif_plug_ovs/ovs.py#L106-L12... > > the backports are propsoed upstream > https://review.opendev.org/q/Id9ef7074634a0f23d67a4401fa8fca363b51bb43 > and we have backported this downstream to adress that performance > regression. > the upstram backport is semi stalled just ebcasue we wanted to > disucss if we shoudl make ti opt in > by default upstream while backporting but it might be helpful for > you if this is related to yoru current > issues. > > 40-55 kpps is kind of low for kernel ovs but if you have a low > clockrate cpu, hybrid_plug + incorrect qos > then i could see you hitting such a bottelneck. > > one workaround by the way without the os-vif workaround backported > is to set > /proc/sys/net/core/default_qdisc to not apply any qos or a low > overhead qos type > i.e. sudo sysctl -w net.core.default_qdisc=pfifo_fast > >
> that may or may not help but i would ensure that your are not usign > somting like fqdel or cake > for net.core.default_qdisc and if you are try changing it to > pfifo_fast and see if that helps. > > there isnet much you can do about the cpu clock rate but ^ is > somethign you can try for free > note it wont actully take effect on an exsitng vm if you jsut change > the default but you can use > tc to also chagne the qdisk for testing. hard rebooting the vm > shoudl also make the default take effect. > > the only other advice i can give assuming kernel ovs is the only > option you have is > > to look at > > https://docs.openstack.org/nova/latest/configuration/config.html#libvirt.rx_... > > https://docs.openstack.org/nova/latest/configuration/config.html#libvirt.tx_... > and > > https://docs.openstack.org/nova/latest/configuration/extra-specs.html#hw:vif... > > if the bottelneck is actully in qemu or the guest kernel rather then > ovs adjusting the rx/tx queue size and > using multi queue can help. it will have no effect if ovs is the > bottel neck. > > > I have set this option to 1024, and enable multiqueue as well. But it did not help.
> > > > On Wed, Sep 6, 2023 at 9:21 AM Ha Noi <hanoi952022@gmail.com> > wrote: > > > > > Hi Satish, > > > > > > Actually, our customer get this issue when the tx/rx above only > 40k pps. > > > So what is the threshold of this throughput for OvS? > > > > > > > > > Thanks and regards > > > > > > On Wed, 6 Sep 2023 at 20:19 Satish Patel <satish.txt@gmail.com> > wrote: > > > > > > > Hi, > > > > > > > > This is normal because OVS or LinuxBridge wire up VMs using > TAP interface > > > > which runs on kernel space and that drives higher interrupt > and that makes > > > > the kernel so busy working on handling packets. Standard > OVS/LinuxBridge > > > > are not meant for higher PPS. > > > > > > > > If you want to handle higher PPS then look for DPDK or SRIOV > deployment. > > > > ( We are running everything in SRIOV because of high PPS > requirement) > > > > > > > > On Tue, Sep 5, 2023 at 11:11 AM Ha Noi <hanoi952022@gmail.com> > wrote: > > > > > > > > > Hi everyone, > > > > > > > > > > I'm using Openstack Train and Openvswitch for ML2 driver and > GRE for > > > > > tunnel type. I tested our network performance between two > VMs and suffer > > > > > packet loss as below. > > > > > > > > > > VM1: IP: 10.20.1.206 > > > > > > > > > > VM2: IP: 10.20.1.154 <https://10.20.1.154/24> > > > > > > > > > > VM3: IP: 10.20.1.72 > > > > > > > > > > > > > > > Using iperf3 to testing performance between VM1 and VM2. > > > > > > > > > > Run iperf3 client and server on both VMs. > > > > > > > > > > On VM2: iperf3 -t 10000 -b 130M -l 442 -P 6 -u -c 10.20.1.206 > > > > > > > > > > On VM1: iperf3 -t 10000 -b 130M -l 442 -P 6 -u -c 10.20.1.154 > > > > > <https://10.20.1.154/24> > > > > > > > > > > > > > > > Using VM3 ping into VM1, then the packet is lost and the > latency is > > > > > quite high. > > > > > > > > > > > > > > > ping -i 0.1 10.20.1.206 > > > > > > > > > > PING 10.20.1.206 (10.20.1.206) 56(84) bytes of data. > > > > > > > > > > 64 bytes from 10.20.1.206: icmp_seq=1 ttl=64 time=7.70 ms > > > > > > > > > > 64 bytes from 10.20.1.206: icmp_seq=2 ttl=64 time=6.90 ms > > > > > > > > > > 64 bytes from 10.20.1.206: icmp_seq=3 ttl=64 time=7.71 ms > > > > > > > > > > 64 bytes from 10.20.1.206: icmp_seq=4 ttl=64 time=7.98 ms > > > > > > > > > > 64 bytes from 10.20.1.206: icmp_seq=6 ttl=64 time=8.58 ms > > > > > > > > > > 64 bytes from 10.20.1.206: icmp_seq=7 ttl=64 time=8.34 ms > > > > > > > > > > 64 bytes from 10.20.1.206: icmp_seq=8 ttl=64 time=8.09 ms > > > > > > > > > > 64 bytes from 10.20.1.206: icmp_seq=10 ttl=64 time=4.57 ms > > > > > > > > > > 64 bytes from 10.20.1.206: icmp_seq=11 ttl=64 time=8.74 ms > > > > > > > > > > 64 bytes from 10.20.1.206: icmp_seq=12 ttl=64 time=9.37 ms > > > > > > > > > > 64 bytes from 10.20.1.206: icmp_seq=14 ttl=64 time=9.59 ms > > > > > > > > > > 64 bytes from 10.20.1.206: icmp_seq=15 ttl=64 time=7.97 ms > > > > > > > > > > 64 bytes from 10.20.1.206: icmp_seq=16 ttl=64 time=8.72 ms > > > > > > > > > > 64 bytes from 10.20.1.206: icmp_seq=17 ttl=64 time=9.23 ms > > > > > > > > > > ^C > > > > > > > > > > --- 10.20.1.206 ping statistics --- > > > > > > > > > > 34 packets transmitted, 28 received, 17.6471% packet loss, > time 3328ms > > > > > > > > > > rtt min/avg/max/mdev = 1.396/6.266/9.590/2.805 ms > > > > > > > > > > > > > > > > > > > > Does any one get this issue ? > > > > > > > > > > Please help me. Thanks > > > > > > > > > > >