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Oleg Vazhnev
Asked: 2012-11-19 06:08:28 +0800 CST

Should I enable "Intel NIC DMA Channels"?

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I have HP DL360p Gen8 646902-xx1 I'm trying to optimize my config for low latency trading.

Should I enable "Intel NIC DMA Channels"? Will that help/affect my system?

From HP doc:

Added a new ROM Based Setup Utility (RBSU) Advanced Performance Option menu that allows the user to enable Intel NIC DMA Channels (IOAT). This option is disabled by default. When enabled, certain networking devices may see an improvement in performance by utilizing Intel's DMA engine to offload network activity. Please consult documentation from the network adapter to determine if this feature is supported.

performance

2 Answers

  1. Best Answer

    If you're asking Server Fault for advice on this, you're definitely not on the leading edge of the hardware/systems side of low-latency design. That's fine, but this is a narrow space, and engineers in the industry tend not to share information.

    I've managed trading systems in multiple environments, and the tuning parameters and tweaks made in one company almost never applied to other firms. Different application code, developers, frameworks, hardware choices, exchange and co-location options all combined to make it impossible to have a single formula for success.

    The one constant throughout this was that there was repeated testing, refactoring and benchmarking involved. E.g. Try both settings and see. Make sure you have a way to measure at the application side. We can't tell you what will work for your environment.

    I think I recall you using Windows for your application, so that's obviously a disadvantage since most people in this space have moved to Linux and nowadays, FPGA solutions for feed-handlers, filtering and strategy, 10GbE throughout, UDP and TCP kernel bypass, etc.

    I don't think I've used an Intel adapter in finance for a few years. It's mostly been Myricom and Solarflare...

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  2. "Will that help/affect my system?" - enable it and find out?

    Seriously, you're the best person to determine if it has or hasn't helped. Unless you want to share a week's worth of baseline performance with us, explain your situation in detail (what performance counters you are trying to improve, user experience before and after, seat of the pants time trials, etc.), then enable it and run performance logs for another week and share them again.

    It is doubtful anyone here will have the same situation/setup as you to give you an accurate answer, but DMA (IOAT) has been shown to increase network performance on machines simply because it frees up the CPU for other duties.

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