I would say let's run your same benchmark with OVS-DPDK and tell me if you see better performance. I doubt you will see significant performance boot but lets see. Please prove me wrong :) On Thu, Sep 7, 2023 at 9:45 PM Ha Noi <hanoi952022@gmail.com> wrote:
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 >> > > > > >> > > > >> >>