• More of my philosophy about the network topology in multicores CPUs..

    From World-News2100@21:1/5 to All on Sat Sep 11 19:02:43 2021
    Hello...


    More of my philosophy about the network topology in multicores CPUs..

    I am a white arab from Morocco, and i think i am smart since i have also invented many scalable algorithms and algorithms..

    I invite you to look at the following video:

    Ring or Mesh, or other? AMD's Future on CPU Connectivity

    https://www.youtube.com/watch?v=8teWvMXK99I&t=904s

    And i invite you to read the following article:

    Does an AMD Chiplet Have a Core Count Limit?

    Read more here:

    https://www.anandtech.com/show/16930/does-an-amd-chiplet-have-a-core-count-limit

    I think i am smart and i say that the above video and the above article
    are not so smart, so i will talk about a very important thing, and it is
    the following, read the following:

    Performance Scalability of a Multi-core Web Server

    https://www.researchgate.net/publication/221046211_Performance_scalability_of_a_multi-core_web_server

    So notice carefully that it is saying the following:

    "..we determined that performance scaling was limited by the capacity of
    the address bus, which became saturated on all eight cores. If this key obstacle is addressed, commercial web server and systems software are well-positioned to scale to a large number of cores."

    So as you notice they were using an Intel Xeon of 8 cores, and the
    application was scalable to 8x but the hardware was not scalable to 8x,
    since it was scalable only to 4.8x, and this was caused by the bus
    saturation, since the Address bus saturation causes poor scaling, and
    the Address Bus carries requests and responses for data, called snoops,
    and more caches mean more sources and more destinations for snoops that
    is causing the poor scaling, so as you notice that a network topology of
    a Ring bus or a bus was not sufficient so that to scale to 8x on an
    Intel Xeon with 8 cores, so i think that the new architectures like Epyc
    CPU and Threadripper CPU can use a faster bus or/and a different network topology that permits to both ensure a full scalability locally in the
    same node and globally between the nodes, so then we can notice that a sophisticated mesh network topology not only permits to reduce the
    number of hops inside the CPU for good latency, but it is also good for reliability by using its sophisticated redundancy and it is faster than previous topologies like the ring bus or the bus since
    for example the search on address bus becomes parallelized, and it looks
    like the internet network that uses mesh topology using routers, so it parallelizes, and i also think that using a more sophisticated topology
    like a mesh network topology is related to queuing theory since we can
    notice that in operational research the mathematics says that we can
    make the queue like M/M/1 more efficient by making the server more
    powerful, but we can notice that
    the knee of a M/M/1 queue is around 75% , so we can notice that
    by using in a mesh topology like internet or inside a CPU you can
    by parallelizing more you can in operational research both enhance the
    knee of the queue and the speed of executing the transactions and it is
    like using many servers in queuing theory and it permits to scale better
    inside a CPU or in internet.


    Thank you,
    Amine Moulay Ramdane.

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