Interrupt moderation and game fps

Discussion in 'Network questions and troubleshooting' started by Maulcun, May 5, 2024.

  1. Maulcun

    Maulcun Member

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    Interrupt moderation (Ethernet) can cause fps drop when is on?


    To reduce the number of interrupts, many NICs use interrupt moderation. With interrupt moderation, the NIC hardware will not generate an interrupt immediately after it receives a packet. Instead, the hardware waits for more packets to arrive, or for a time-out to expire, before generating an interrupt. The hardware vendor specifies the maximum number of packets, time-out interval, or other interrupt moderation algorithm.

    The measured round-trip time for a packet is one of the most commonly used techniques to determine the network bandwidth between two endpoints. However, when interrupt moderation is enabled, receiving a packet does not generate an immediate interrupt and therefore the perceived round-trip time for a particular packet becomes larger than the average time. To allow accurate measurement of round trip time for a packet, NDIS provides the ability to disable and enable interrupt moderation on demand.

    https://learn.microsoft.com/en-us/windows-hardware/drivers/network/interrupt-moderation
     
  2. mbk1969

    mbk1969 Ancient Guru

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    @Maulcun

    Interrupt moderation produces less interrupts from NIC, so how do link that to FPS?
     
  3. Ghosty

    Ghosty Ancient Guru

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    Use a game engine like Unreal to test or a networked PC.
     
  4. 386SX

    386SX Ancient Guru

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    I don't know the effects on gaming, but in general you would like to have interrupt moderation to have a performant network to ease the load on your hardware, or "spread it evenly" by offloading stuff to the NIC if possible.
    I could think of this offloading and moderating maybe be an issue for gaming, as gaming prefers data in realtime instead of "cached". Interrupt moderation collects data and then sents it as a bulk instead of sending each chunk of data right away.

    If you think of online games: you want to know where the enemy is right away, not "after enough packts came in so it deserves an interrupt".

    If you disable interrupt moderation be prepared for additional CPU/NIC overhead.
     

  5. fantaskarsef

    fantaskarsef Ancient Guru

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    Having played around with ping issues when I set up my current rig a few months ago I did not notice any FPS difference in the games I tested because of ping issues.
    Network performance is another thing, but I seriously doubt you feel any impact on system performance related to tasks other than network traffic, e.g. rendering.
     
  6. I remember reading somewhere that if you have a slow internet, disabling interrupt moderation could be beneficial.
    Have not seen any benefit from doing so though, neither in gaming nor internet "responsiveness"
     
    386SX likes this.

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