GCP-dev team @jeroe...@google.com <jeroe...@google.com> @rush...@google.com <rush...@google.com> @joshw...@google.com <joshw...@google.com> Please do check on this & get back.
On Fri, Dec 6, 2024 at 4:24 AM Mukul Sinha <mukul.si...@broadcom.com> wrote: > Thanks @maxime.coque...@redhat.com > Have included dev@dpdk.org > > > On Fri, Dec 6, 2024 at 2:11 AM Maxime Coquelin <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>> 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. >> > >> > @ 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. 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