5 ms·
16 iperf threads...sending at what packet size? Do you understand the notion of line rate? 85Gbps at 1500B is only 7MPPS, which is half of 10Gbps at line rate
by ra1n85 7y ago
16 iperf threads...sending at what packet size? Do you understand the notion of line rate? 85Gbps at 1500B is only 7MPPS, which is half of 10Gbps at line rate.
- toast0 7y agoDoes line rate imply smallest packets? For CDN style use cases, you want to use the whole pipe, and it's going to be mostly larger packets.
- ra1n85 7y agoYes. The point of discussion here is that the Linux kernel struggles to do line rate 10Gbps. This was misinterpreted as "the Linux kernel struggles to do 10Gbps".
- Dylan16807 7y agoWhere are you getting your definitions? I have never seen "line rate" used to refer to packets per second.
- ra1n85 7y agoIt implies it. Ethernet at 84B per frame is the smallest you can go, thus the line rate - some examples: https://events19.linuxfoundation.org/wp-content/uploads/2017/12/jim-Thompson.pdf https://events19.linuxfoundation.org/wp-content/uploads/2017... https://www.redhat.com/en/blog/pushing-limits-kernel-networking https://www.redhat.com/en/blog/pushing-limits-kernel-network... https://kernel-recipes.org/en/2014/ndiv-a-low-overhead-network-traffic-diverter/ https://kernel-recipes.org/en/2014/ndiv-a-low-overhead-netwo...
- Dylan16807 7y ago"How do you fill a 100GBps pipe with small packets?" "achieve 10 Gbps line rate at 60B frames" "reaching line rate on all packet sizes" Line rate is just bits per second. You have to add in a qualifier about packet size before you're talking about packets per second.
- ra1n85 7y agoNope, I'm sorry you're not quite getting it here. Minimum Ethernet frame is 84B on the wire - it's simple enough from there.
- big_chungus 7y agoI've never heard this weird qualification for the definition of "line rate" that it somehow requires minimum packet size, so I looked it up. The first three sources for a quoted big-g search all imply or directly state that it's the same as bandwidth: https://blog.ipspace.net/2009/03/line-rate-and-bit-rate.html https://blog.ipspace.net/2009/03/line-rate-and-bit-rate.html https://www.reddit.com/r/networking/comments/4tk2to/bandwidth_vs_line_rate_vs_throughput_vs/ https://www.reddit.com/r/networking/comments/4tk2to/bandwidt... https://www.fmad.io/blog-what-is-10g-line-rate.html https://www.fmad.io/blog-what-is-10g-line-rate.html Also, for gigabit networks, ethernet packets are padded to at least 512 bytes because of a bigger slot size: https://www.cse.wustl.edu/~jain/cis788-97/ftp/gigabit_ethernet/index.html https://www.cse.wustl.edu/~jain/cis788-97/ftp/gigabit_ethern...
- shaklee3 7y agoLine rate doesn't imply small packets. But most userspace benchmarking uses 64B packets. That being said, the "imix" packet size, which is supposed to represent internet traffic, is around 500B.
- kingosticks 7y agoThere are numerous imix definitions floating around now, it really depends on who you ask. The more realistic ones define a pattern of different sized packets. And performance varies greatly depending on which imix flavour you use, which probably goes back to the earlier poster's 'dumpster fire' comment (although I don't know exactly what NPU generation they are referring to).
- Hikikomori 7y agoLine rate does imply pps at the smallest sized frames in the context of networking equipment performance. Vendors use it extensively in their docs. 64B is the minimum frame size in Ethernet, including interframe gap and preamble its 84B on the wire. It is the same with Ethernet, Gigabit Ethernet and even 100Gbit Ethernet, that source is not correct. https://kb.juniper.net/InfoCenter/index?page=content&id=KB14737 https://kb.juniper.net/InfoCenter/index?page=content&id=KB14...
- bogomipz 7y agoNo, PPS and bandwidth are two distinct metrics. Although there can be a linear relationship between them line rate does not always imply a payload equal or close to the interface MTU. You see this with network vendors and some of the higher end gear. Network vendors always give specs for their gear by quoting both metrics. And there is some gear that that is capable of doing line rates even with small packets, example the Cisco ASR 1000: "For example, because one of the newest Cisco routers, the Cisco ASR 1000 Series Router, is capable of forwarding packets at up to 16 Mp/s with services enabled, it can support the processing of the equivalent of 10 Gb/s of traffic at line rate, with services, even for small packets."[1] [1] https://tools.cisco.com/security/center/resources/network_performance_metrics https://tools.cisco.com/security/center/resources/network_pe...