Open Stack

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 at gmail.com> wrote:

> Dear Smoney,
>
>
>
> On Thu, Sep 7, 2023 at 12:41 AM <smooney at 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-L125
>>
>> 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_queue_size
>>
>> https://docs.openstack.org/nova/latest/configuration/config.html#libvirt.tx_queue_size
>> and
>>
>> https://docs.openstack.org/nova/latest/configuration/extra-specs.html#hw:vif_multiqueue_enabled
>>
>> 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 at 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 at 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 at 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
>> > > > >
>> > > >
>>
>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.openstack.org/pipermail/openstack-discuss/attachments/20230907/cbea9470/attachment.htm>