Hi Maxime, We have run perf top on dpdk-20.05 vs dpdk-22.11 but nothing of difference in the top-hitter api's. In our analysis virtio-PMD CPU performance's not a bottleneck (infact its more performant now) but its the GCP hypervisor which isn't able to cope up with 3 times the Tx traffic load.
On Fri, Dec 6, 2024 at 1:54 PM Maxime Coquelin <maxime.coque...@redhat.com> wrote: > Hi Mukul, > > On 12/5/24 23:54, Mukul Sinha wrote: > > Thanks @maxime.coque...@redhat.com <mailto:maxime.coque...@redhat.com> > > Have included dev@dpdk.org <mailto:dev@dpdk.org> > > > > > > On Fri, Dec 6, 2024 at 2:11 AM Maxime Coquelin > > <maxime.coque...@redhat.com <mailto:maxime.coque...@redhat.com>> wrote: > > > > Hi Mukul, > > > > DPDK upstream mailing lists should be added to this e-mail. > > I am not allowed to provide off-list support, all discussions should > > happen upstream. > > > > If this is reproduced with downtream DPDK provided with RHEL and you > > have a RHEL subscription, please use the Red Hat issue tracker. > > > > Thanks for your understanding, > > Maxime > > > > On 12/5/24 21:36, Mukul Sinha wrote: > > > + Varun > > > > > > On Fri, Dec 6, 2024 at 2:04 AM Mukul Sinha > > <mukul.si...@broadcom.com <mailto:mukul.si...@broadcom.com> > > > <mailto:mukul.si...@broadcom.com > > <mailto:mukul.si...@broadcom.com>>> wrote: > > > > > > Hi GCP & Virtio-PMD dev teams, > > > We are from VMware NSX Advanced Load Balancer Team whereby in > > > GCP-cloud (*custom-8-8192 VM instance type 8core8G*) we are > > triaging > > > an issue of TCP profile application throughput performance > with > > > single dispatcher core single Rx/Tx queue (queue depth: 2048) > the > > > throughput performance we get using dpdk-22.11 virtio-PMD > code is > > > degraded significantly when compared to when using dpdk-20.05 > PMD > > > We see high amount of Tx packet drop counter incrementing on > > > virtio-NIC pointing to issue that the GCP hypervisor side is > > unable > > > to drain the packets faster (No drops are seen on Rx side) > > > The behavior is like this : > > > _Using dpdk-22.11_ > > > At 75% CPU usage itself we start seeing huge number of Tx > packet > > > drops reported (no Rx drops) causing TCP restransmissions > > eventually > > > bringing down the effective throughput numbers > > > _Using dpdk-20.05_ > > > even at ~95% CPU usage without any packet drops (neither Rx > > nor Tx) > > > we are able to get a much better throughput > > > > > > To improve performance numbers with dpdk-22.11 we have tried > > > increasing the queue depth to 4096 but that din't help. > > > If with dpdk-22.11 we move from single core Rx/Tx queue=1 to > > single > > > core Rx/Tx queue=2 we are able to get slightly better numbers > > (but > > > still doesnt match the numbers obtained using dpdk-20.05 > > single core > > > Rx/Tx queue=1). This again corroborates the fact the GCP > > hypervisor > > > is the bottleneck here. > > > > > > To root-cause this issue we were able to replicate this > behavior > > > using native DPDK testpmd as shown below (cmds used):- > > > Hugepage size: 2 MB > > > ./app/dpdk-testpmd -l 0-1 -n 1 -- -i --nb-cores=1 --txd=2048 > > > --rxd=2048 --rxq=1 --txq=1 --portmask=0x3 > > > set fwd mac > > > set fwd flowgen > > > set txpkts 1518 > > > start > > > stop > > > > > > Testpmd traffic run (for packet-size=1518) for exact same > > > time-interval of 15 seconds: > > > > > > _22.11_ > > > ---------------------- Forward statistics for port 0 > > > ---------------------- > > > RX-packets: 2 RX-dropped: 0 > > RX-total: 2 > > > TX-packets: 19497570 *TX-dropped: 364674686 * TX-total: > > 384172256 > > > > > > > > > ---------------------------------------------------------------------------- > > > _20.05_ > > > ---------------------- Forward statistics for port 0 > > > ---------------------- > > > RX-packets: 3 RX-dropped: 0 > > RX-total: 3 > > > TX-packets: 19480319 TX-dropped: 0 > TX-total: > > > 19480319 > > > > > > > > > ---------------------------------------------------------------------------- > > > > > > As you can see > > > dpdk-22.11 > > > Packets generated : 384 million Packets serviced : ~19.5 > > million : > > > Tx-dropped : 364 million > > > dpdk-20.05 > > > Packets generated : ~19.5 million Packets serviced : ~19.5 > > million : > > > Tx-dropped : 0 > > > > > > Actual serviced traffic remains almost same between the two > > versions > > > (implying the underlying GCP hypervisor is only capable of > > handling > > > that much) but in dpdk-22.11 the PMD is pushing almost 20x > > traffic > > > compared to dpdk-20.05 > > > The same pattern can be seen even if we run traffic for a > longer > > > duration. > > > > > > > =============================================================================================== > > > > > > Following are our queries: > > > @ Virtio-dev team > > > 1. Why in dpdk-22.11 using virtio PMD the testpmd application > is > > > able to pump 20 times Tx traffic towards hypervisor compared > to > > > dpdk-20.05 ? > > > What has changed either in the virtio-PMD or in the > virtio-PMD & > > > underlying hypervisor communication causing this behavior ? > > > If you see actual serviced traffic by the hypervisor remains > > almost > > > on par with dpdk-20.05 but its the humongous packets drop > count > > > which can be overall detrimental for any DPDK-application > running > > > TCP traffic profile. > > > Is there a way to slow down the number of packets sent > > towards the > > > hypervisor (through either any code change in virtio-PMD or > any > > > config setting) and make it on-par with dpdk-20.05 > performance ? > > > 2. In the published Virtio performance report Release 22.11 > > we see > > > no qualification of throughput numbers done on GCP-cloud. Is > > there > > > any internal performance benchmark numbers you have for > GCP-cloud > > > and if yes can you please share it with us so that we can > > check if > > > there's any configs/knobs/settings you used to get optimum > > performance. > > > I don't know what your issue is, but this is not something we noticed > using QEMU/KVM as hypervisor with Vhost-user backend. > > I would suggest you run a git bisect to pinpoint to the specific commit > introducing this regression. > > Also, you could run perf top in the guest on both 20.05 and 22.11, maybe > we could spot something in it. > > Regards, > Maxime > > > > > > > @ GCP-cloud dev team > > > As we can see any amount of traffic greater than what can be > > > successfully serviced by the GCP hypervisor is all getting > > dropped > > > hence we need help from your side to reproduce this issue in > your > > > in-house setup preferably using the same VM instance type as > > > highlighted before. > > > We need further investigation by you from the GCP host level > > side to > > > check on parameters like running out of Tx buffers or Queue > full > > > conditions for the virtio-NIC or number of NIC Rx/Tx kernel > > threads > > > as to what is causing hypervisor to not match up to the > > traffic load > > > pumped in dpdk-22.11 > > > Based on your debugging we would additionally need inputs as > > to what > > > can be tweaked or any knobs/settings can be configured from > the > > > GCP-VM level to get better performance numbers. > > > > > > Please feel free to reach out to us for any further queries. > > > > > > _Additional outputs for debugging:_ > > > lspci | grep Eth > > > 00:06.0 Ethernet controller: Red Hat, Inc. Virtio network > device > > > root@dcg15-se-ecmyw:/home/admin/dpdk/build# ethtool -i eth0 > > > driver: virtio_net > > > version: 1.0.0 > > > firmware-version: > > > expansion-rom-version: > > > bus-info: 0000:00:06.0 > > > supports-statistics: yes > > > supports-test: no > > > supports-eeprom-access: no > > > supports-register-dump: no > > > supports-priv-flags: no > > > > > > testpmd> show port info all > > > ********************* Infos for port 0 ********************* > > > MAC address: 42:01:0A:98:A0:0F > > > Device name: 0000:00:06.0 > > > Driver name: net_virtio > > > Firmware-version: not available > > > Connect to socket: 0 > > > memory allocation on the socket: 0 > > > Link status: up > > > Link speed: Unknown > > > Link duplex: full-duplex > > > Autoneg status: On > > > MTU: 1500 > > > Promiscuous mode: disabled > > > Allmulticast mode: disabled > > > Maximum number of MAC addresses: 64 > > > Maximum number of MAC addresses of hash filtering: 0 > > > VLAN offload: > > > strip off, filter off, extend off, qinq strip off > > > No RSS offload flow type is supported. > > > Minimum size of RX buffer: 64 > > > Maximum configurable length of RX packet: 9728 > > > Maximum configurable size of LRO aggregated packet: 0 > > > Current number of RX queues: 1 > > > Max possible RX queues: 2 > > > Max possible number of RXDs per queue: 32768 > > > Min possible number of RXDs per queue: 32 > > > RXDs number alignment: 1 > > > Current number of TX queues: 1 > > > Max possible TX queues: 2 > > > Max possible number of TXDs per queue: 32768 > > > Min possible number of TXDs per queue: 32 > > > TXDs number alignment: 1 > > > Max segment number per packet: 65535 > > > Max segment number per MTU/TSO: 65535 > > > Device capabilities: 0x0( ) > > > Device error handling mode: none > > > > > > > > > > > > This electronic communication and the information and any files > > > transmitted with it, or attached to it, are confidential and are > > > intended solely for the use of the individual or entity to whom > > it is > > > addressed and may contain information that is confidential, > legally > > > privileged, protected by privacy laws, or otherwise restricted > from > > > disclosure to anyone else. If you are not the intended recipient > > or the > > > person responsible for delivering the e-mail to the intended > > recipient, > > > you are hereby notified that any use, copying, distributing, > > > dissemination, forwarding, printing, or copying of this e-mail is > > > strictly prohibited. If you received this e-mail in error, please > > return > > > the e-mail to the sender, delete it from your computer, and > > destroy any > > > printed copy of it. > > > > > > This electronic communication and the information and any files > > transmitted with it, or attached to it, are confidential and are > > intended solely for the use of the individual or entity to whom it is > > addressed and may contain information that is confidential, legally > > privileged, protected by privacy laws, or otherwise restricted from > > disclosure to anyone else. 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