Microsoft Windows Bug Is Holding Back AMD Ryzen

Discussion in 'Frontpage news' started by Hilbert Hagedoorn, Mar 10, 2017.

  1. Hilbert Hagedoorn

    Hilbert Hagedoorn Don Vito Corleone Staff Member

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    We've been adressing the topic widely in our reviews, it makes little sense for Ryzen processors that are that powerful to not perform as well in games in CPU bound situations. Microsoft now kind of confirms the issue that Windows 10 does not detect the simulated SMT threads properly, and the simulated SMT threads are weaker compared to real CPU cores. This could hinder the game performance.

    http://www.guru3d.com/news-story/microsoft-confirms-windows-bug-is-holding-back-amd-ryzen.html
     
  2. Ziggymac

    Ziggymac Member Guru

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    People are going to be very disappointed if they expect this to result in big frame rate jumps, suddenly making R7's match or outperform 7700k's in gaming.

    ..the scheduling fix will almost certainly result in better frame rates but more in line with a GPU driver update, maybe an extra 4-5fps rather than the jump in performance you'd get replacing your current GPU with a faster one.
     
  3. Neo Cyrus

    Neo Cyrus Ancient Guru

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    So the SMT threads are incorrectly detected as full blown core threads?... Pretty much what everyone suspected.
     
  4. Lane

    Lane Ancient Guru

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    It dont need .. it is an octa core with 2 times more performance in multithreaded appliccations. But some games was running strangely compared to the 6900K.
     

  5. Ziggymac

    Ziggymac Member Guru

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    Maybe, but people haven't been disappointed with Ryzen's gaming performance compared to a 6900 but the 7700K..and that's the benchmark people will hold it it against.

    They shouldn't, as the R5 1500 & 1600 are the real Ryzen competitors to the i5 & I7's, but there you go.
     
  6. AlmondMan

    AlmondMan Master Guru

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    Yes, and that whole comparison is absurd. More threads is fine, but it'll take a while before more threads are able to catch up to a 20% lower coreclock when performance pr clock is almost the same...
     
  7. rl66

    rl66 Ancient Guru

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    it's like the Pentium aniversary, once patched it work really really great (for a 50 Euro CPU it work better than most I3 once OC)... but at launch: bug with OS and game.

    1st buyer do the testing job :) never buy the 1st.
     
  8. xIcarus

    xIcarus Master Guru

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    I don't understand this one. Theoretically either of the hardware threads attached to a core can saturate that core, no? Just not both at the same time.
     
  9. Neo Cyrus

    Neo Cyrus Ancient Guru

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    Let me explain it from what I understand, someone correct me if I'm wrong.

    The SMT thread uses leftover or unused resources of a core to get maximum use out of the core.

    A core is made of many components, and even if it's used to "100%" as Windows's task manager (but not others) may show, it's not common for all the parts of the core to actually be in use at the same time. A program is pretty much never (aside from stress tests) going to use exactly all the resources a core has, it needs certain amounts of certain things in a certain ratio, that means there will be something left unused generally and can't make use of that remainder because there isn't enough of other resources (the ratio I talked about). SMT is a clever way of scheduling to make use of those available resources which adds up to quite a bit when you have multiple cores.

    So this means the SMT thread is nowhere near as powerful as the main thread of the core, it's not simply 2 threads attached to one core. One is a standard thread, the other is cleverly using leftover resources. Both threads have to be in use at the same time to saturate a core.

    Though I thought I read in the past that Intel (at the time, this was a long time ago) did include a minor amount of extra physical components in their SMT CPUs. This was so long ago it may have been with a Netburst chip or derivative with their first implementation of Hyper Threading. I have no idea if that still holds true today, but I doubt it. I've asked about this at least once before but no one had an answer.
     
    Last edited: Mar 10, 2017
  10. ddelamare

    ddelamare Master Guru

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    Dat "threaad-schedulur" though... :p
     

  11. JonasBeckman

    JonasBeckman Ancient Guru

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    Wonder if this still happens with the current Win10 RS2 insider builds? (15048 should have hit slow-ring yesterday, 1505x will probably hit the fast ring either later today or next week if it gets delayed.)
     
  12. moeppel

    moeppel Member Guru

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    Futher Ryzen consists of CCXs (Core Complexes, in R7's case 2 CCXs with 4 Cores each) - Due to architecure and the nature of Ryzen it's further helpful to have threads and resources reside in the same CCX insofar the threads are dependent on one another.

    Interal CCX communication is a lot faster than cross CCX communication. Having threads which depend on one another run in a different CCX increases latency unnecessarily.

    That said, I've absolutely no idea how much a proper scheduling could get out of Ryzen. I'd expect anywhere from 5~10% but that may just be completely wishful already.

    Time will tell.
     
  13. Neo Cyrus

    Neo Cyrus Ancient Guru

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    I just realized there was a mistake in my post, and it's too late to edit it again. A stress test in fact doesn't make full use of a core, that's why SMT in such an artificial benchmark will yield much better results.

    I'm super tired, what was going through my brain as I was typing that, is that a stress test (some, not all) is one of the few things that can saturate a core properly for both threads. That's what I was thinking of when I said it can make full use of a core. In my half asleep state that somehow translated into the wrong statement. Sorry.
     
  14. nevcairiel

    nevcairiel Master Guru

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    One would think AMD would be smart enough to work with Microsoft to have this sorted out in Windows 10 for the processor launch. Especially after their last processor architecture which needed Windows scheduling changes as well, and happened only after the launch. But apparently not.
     
  15. SirDremor

    SirDremor Master Guru

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    If this is an issue in Windows 10, why does this affect only Ryzen?
    Or is Intel also somehow affected by this?
     

  16. Neo Cyrus

    Neo Cyrus Ancient Guru

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    Read my earlier posts in this thread and moeppel's post as well.

    The TL;DR is that it only affects Ryzen because their implementation of SMT isn't detected properly by Windows. If you want more details read the posts.
     
  17. DARKSF

    DARKSF Active Member

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    I still wait to see does anyone plan to make a Windows 7 vs Windows 10 shootout on Ryzen or you are all just too scared from Microsoft.
    And if you gonna give me the OLD OS reason go look at Steam statistics Windows 10 is loosing share for a second month in a roll and Windows 7 is gaining share on the Steam userbase.
     
  18. Neo Cyrus

    Neo Cyrus Ancient Guru

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    It's already been done with past CPUs. On Intel CPUs it's not going to make any difference, the results were always plus or minus an absolute maximum of 2%, usually 1% or less which is within margin of error. With AMD CPUs it might actually matter, especially after Windows 10 is updated to properly use Ryzen. Might. We'll see.

    If what you're saying is that you want to see proof that Ryzen chips will actually perform better on Windows 10 (once updated) than Windows 7 before considering Win 10 worthwhile, then don't bother. Straight up performance on what's currently available is not the reason to upgrade to Windows 10.
     
    Last edited: Mar 10, 2017
  19. SirDremor

    SirDremor Master Guru

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    Actually I've read all posts before posting my question.
    Your posts don't have any definite answer, only elaborations on what might cause the issue.
    Your posts don't have info on Intel's HT either, so even if we know that HT cores are recognized correctly, there's no guarantee Windows works absolutely correct with such cores. So, in theory, any fix from them can also affect Intel's CPUs.
    I am not saying this will be the case, but at least there's nothing pointing to the contrary.
     
  20. Neo Cyrus

    Neo Cyrus Ancient Guru

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    Let me be perfectly clear then: Windows already properly uses Intel's Hyper Threading. There are no foreseeable performance improvements for Intel's implementation of SMT through Windows updates. Meanwhile AMD's implementation of SMT is not being used properly at all by Windows.

    This is why I'm hoping there will be some real, notable, improvements to Ryzen's performance once Windows is updated. Who knows if it'll actually be a notable amount, we'll see.
     

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