Floating Point

The key highlight improvement for floating point performance is full AVX2 support. AMD has increased the execution unit width from 128-bit to 256-bit, allowing for single-cycle AVX2 calculations, rather than cracking the calculation into two instructions and two cycles. This is enhanced by giving 256-bit loads and stores, so the FMA units can be continuously fed. AMD states that due to its energy aware scheduling, there is no predefined frequency drop when using AVX2 instructions (however frequency may be reduced dependent on temperature and voltage requirements, but that’s automatic regardless of instructions used)

In the floating point unit, the queues accept up to four micro-ops per cycle from the dispatch unit which feed into a 160-entry physical register file. This moves into four execution units, which can be fed with 256b data in the load and store mechanism.

Other tweaks have been made to the FMA units than beyond doubling the size – AMD states that they have increased raw performance in memory allocations, for repetitive physics calculations, and certain audio processing techniques.

Another key update is decreasing the FP multiplication latency from 4 cycles to 3 cycles. That is quite a significant improvement. AMD has stated that it is keeping a lot of the detail under wraps, as it wants to present it at Hot Chips is August. We’ll be running a full instruction analysis for our reviews on July 7th.

Decode Integer Units, Load and Store
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  • BMNify - Saturday, June 22, 2019 - link

    the only real world test that matters in the UHD2/8K Rec. 2020/BT.2020 LIVE NHK/bbc broadast of the 2020 Summer Olympics will begin on Friday, 24 July and related video streams is can AMD Zen 2 do it can any pc core do realtime x264/x265/ffmpeg software encoding and x264/x265 compliant decoding (notice how many hw assisted encoders today dont decode to spec as seen when you re-enode them with the latest ffmpeg), how many 8k encodes and what overheads are remaining if any can even do one... Reply
  • stance_changer - Sunday, June 23, 2019 - link

    Does IF use PCI E? I thought it used the wiring in 2p epyc systems, and IIRC PCI E doesn't double the bus width every gen, but I would love to be proven wrong. Reply
  • SlitheryDee - Friday, June 28, 2019 - link

    I've been using intel for a few years now, but I must say I can't describe how much I love what AMD is doing these days. I go where the performance per dollar is generally, so the best complement I can pay them is to say my next upgrade will be based on an AMD chip. Reply
  • SlyNine - Sunday, July 7, 2019 - link

    So, what time exactly do these new cpus launch. I mean. The hour. Reply
  • Dodozoid - Sunday, July 7, 2019 - link

    Yeah, I was also trying to find that information with no success.
    Do the reviewers know already or are they waiting for a release instruction from AMD?
    Reply
  • ilux.merks - Sunday, July 7, 2019 - link

    What nobody is talking about is how are the fixes for meltdown and spectre on these new amd processors? Reply
  • Korguz - Sunday, July 7, 2019 - link

    simple.. they dont exist, from what i have seen.. those issues.....are intels only ... Reply

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