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Microsoft Security Windows

Microsoft Details Performance Impact of Spectre and Meltdown Mitigations on Windows Systems (microsoft.com) 237

Microsoft's Windows chief Terry Myerson on Tuesday outlined how Spectre and Meltdown firmware updates may affect PC performance. From a blog post: With Windows 10 on newer silicon (2016-era PCs with Skylake, Kabylake or newer CPU), benchmarks show single-digit slowdowns, but we don't expect most users to notice a change because these percentages are reflected in milliseconds.

With Windows 10 on older silicon (2015-era PCs with Haswell or older CPU), some benchmarks show more significant slowdowns, and we expect that some users will notice a decrease in system performance. With Windows 8 and Windows 7 on older silicon (2015-era PCs with Haswell or older CPU), we expect most users to notice a decrease in system performance.

Windows Server on any silicon, especially in any IO-intensive application, shows a more significant performance impact when you enable the mitigations to isolate untrusted code within a Windows Server instance. This is why you want to be careful to evaluate the risk of untrusted code for each Windows Server instance, and balance the security versus performance tradeoff for your environment.

For context, on newer CPUs such as on Skylake and beyond, Intel has refined the instructions used to disable branch speculation to be more specific to indirect branches, reducing the overall performance penalty of the Spectre mitigation. Older versions of Windows have a larger performance impact because Windows 7 and Windows 8 have more user-kernel transitions because of legacy design decisions, such as all font rendering taking place in the kernel.

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Microsoft Details Performance Impact of Spectre and Meltdown Mitigations on Windows Systems

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  • Planned Obsolescence (Score:5, Interesting)

    by xxxJonBoyxxx ( 565205 ) on Tuesday January 09, 2018 @01:20PM (#55894891)
    >> With Windows XX on older silicon (2015-era PCs with Haswell or older CPU)...we expect...a decrease in system performance. (So plan to buy a new proc from our licensed PC distributors soon.)
    • With "Older" silicon, you can probably buy a faster CPU to put into your older motherboard. It's not really a "NEW" CPU, just a faster one to compensate for the performance hit.
      •     Except Intel changes the socket format so frequently, I've almost always been forced to by a new motherboard... and new memory.

    • by dyfet ( 154716 )

      Indeed...translation; "Intel fucked up, and we fucked it up even more in our crappy design decisions, but we are both going to make huge profits from selling everyone new hardware and software, so all is good."

  • Kudos to Microsoft and Terry Myerson - great article with excellent details...

    as long as you're running an Intel processor. Inquiring minds want to know where in the performance-hit list a Ryzen shows up. Does it have the " refined...instructions used to disable branch speculation to be more specific to indirect branches, reducing the overall performance penalty of the Spectre mitigation."?

    • Kudos to Microsoft and Terry Myerson - great article with excellent details...

      It's a well laid out article, but it's a shame they've shied away from posting any actual numbers, leaving us to guess what kind of impact they're talking about, and for everyone to have to run their own benchmarks. They could have said something like "typically xx-xx%, with workloads having heavy I/O most affected".

  • Time to upgrade (Score:3, Interesting)

    by postmortem ( 906676 ) on Tuesday January 09, 2018 @01:22PM (#55894915) Journal

    Folks, your CPUs 2015 and older are obsolete ... how convenient for Wintel.. get that fancy new CPU and another copy of Windows 10, because what you have today is OEM version, so with a new CPU you'll need a new Windows copy.

    • "Obsolete"? My home PC just blue screened from outrage at such a statement. Its Deneb processor from 2009 is just fine, thank you, and even ran DOOM 2016 acceptably (well, it did after I stole my son's video card).
      Methinks your definition of Obsolete is different than mine...

    • Folks, your CPUs 2015 and older are obsolete ... how convenient for Wintel.. get that fancy new CPU and another copy of Windows 10, because what you have today is OEM version, so with a new CPU you'll need a new Windows copy.

      I am on windows 7 using a 2011 made i5-2500K and after upgrading GPU and switching to SSD the machines performance is still good enough to run things like PlayerUnknowns Battlegrounds on Ultra setting(GTA 5 is a bit choppy on ultra but runs buttery smooth on high).. And I haven't even overclocked the CPU yet.

      I am yet to install the patches, but if the performance degrades beyond tolerable I'll first crank the OC to max, maybe try to find a deal on a faster socket 1155 processor as there are couple..

      B

      • Spectre is actually applicable to Intel, AMD, and the various ARMs (Samsung, Qualcomm, ...)

        You're thinking of Meltdown, that's Intel specific.

  • by PingSpike ( 947548 ) on Tuesday January 09, 2018 @01:28PM (#55895005)
    That's the nice Windows 7 you got there. It'd be a real shame if something happened to its performance.
    • by cogeek ( 2425448 )
      Winning!
  • I don't think this is really that surprising. Modern CPU's are almost like mini-computers in themselves breaking down and reorganizing code on the fly internally. Fixing them means ugly workarounds which will usually cost a bit in performance. As time goes on, expect more of these issues rather than less. It's why most modern CPUs have a BIOS loaded table that makes workaround fixes in hardware although this problem is probably too big to fix there.

    • I know I share many slashdotters reticence to try out some of the latest smart devices for fears of the security holes therein, I wonder if there will be a new interest in processors that just brute force everything through without any 'tricks' that could be exploited? I suppose that might be impossible to achieve and have compatibility with the rest of modern computing platforms; I don't know much about what instruction requirements might be needed to keep up with current Windows and Linux if these securi
      • You could make it fully compatible with x86, no problem. That's not the issue at all.

        The cost would be much more than 10% of performance. OOO and speculative execution would probably cost at least 50% of the performance (and, for mobile, this is perf/watt, which translates directly into usable battery life).

        Think about it this way: the CPU hits a plain old branch. The branch has a condition variable that's in L3 or main memory. In your "brute force" model, the processor sits idle for 200-300 instructions wh

    • by 110010001000 ( 697113 ) on Tuesday January 09, 2018 @02:01PM (#55895303) Homepage Journal
      "Modern CPU's are almost like mini-computers"

      Genius!
  • Sounds like this isn't a big issue after all. Good job by Microsoft and Intel with their timely fixes!
    • Want to make it sound more impressive? Microsoft currently has 45 supported variants of Windows. They shipped patches for 41 of those versions.

      Of course, it's crazy to support so many different variants. At the same time it's crazy to support Windows 7 for years after 10 comes out, but people will complain mightily if you EOL it and don't provide security patches.

      And it's even more crazy that none of this was Microsoft's fault to begin with.

  • I've got a Windows machine just for playing games. I don't have any sensitive information in the machine, nor do I really care if I have to reinstall at any point (slightly annoying). So, how can I say to Microsoft "Thanks for looking out for me, but I'd rather the extra performance"?

    Note that the machine on which I game is from 2015 so the "fix" would have a noticeable slowdown. I've already turned off automatic updates, but this would likely be classes as an emergency update which ignores the settings.

    • by Megane ( 129182 )

      The thing about all this is: Why should I care?

      Sure, this is a potentially big problem for people who run virtual server farms, but for my Windows game box (which runs Windows 7, and has had updates turned off since all that "gwx" bullshit), what is the point? Even if I did get it in malware (how? I don't do general web browsing on that computer, just one or two specific games, not even Steam, it's behind NAT, and I also disable a lot of useless services), they would do better to force ads on me... oh wait

  • we don't expect most users to notice a change because these percentages are reflected in milliseconds.

    Most users don't even notice that percentages are dimensionless, so it makes no sense to translate them to milliseconds.Yes, I understand that he pretends to mean that the penalty for each instance of the problem only causes a delay of milliseconds, but still, the performance drop is there and many consecutive penalties aggregate into a noticeable slowdown.

    Apart from this joke, this is a good move from MS.

  • by jonwil ( 467024 ) on Tuesday January 09, 2018 @06:22PM (#55896989)

    I am running a Skylake Core i5-6500 with 8GB RAM and a 250GB Samsung SSD with Windows 7 Home Premium and I have the patch installed and haven't observed any slowdowns.

    Just kicked of a full compile (in VS 2017) of a large (~2100 files) project I have here and I saw no noticeable slowdowns compared to how fast the thing compiled before the patch. And such a thing would be highly I/O bound (reading all the input source files and things, writing out compiled obj and other files, reading toolchain binaries etc) and likely making a lot of kernel-user transitions.

    I have no games on here that are demanding enough to show any observable difference between old and new so I cant test those.

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