Windows 10: How do I disable all the Spectre and Meltdown mitigations in Windows 10 1903?

WAUZZZ8CB4 · May 30, 2019

I have a suspicion that one of them caused a performance regression in an application and I just want to test that hypothesis by disabling these fixes and comparing numbers.

However with the Microsoft guide and the registry tweaks or with InSpectre I can't disable all of the mitigations.

In fact I've found no way to disable L1TF (Foreshadow) and SSBD (Spectre v4) mitigations specifically, only Meltdown and Spectre v2.

Is this something that's hard-coded or are there methods of disabling these?

Thanks

:)

biffzinker · May 30, 2019

Performance Impact on Windows Systems with Spectre and Meltdown Mitigations

Quoting this from the source link at the bottom of my post.

In general, our experience is that Variant 1 and Variant 3 mitigations have minimal performance impact, while Variant 2 remediation, including OS and microcode, has a performance impact.

Performance impact summary:

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 trade-off 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.
Click to expand...

Source: Understanding the performance impact of Spectre and Meltdown mitigations on Windows Systems

nem.. · May 30, 2019

Intel Releases CPU Benchmarks with Meltdown and Spectre Mitigations

official Microsoft report of the impact on performance this would be variable according to the hardware / operating system.

link, https://cloudblogs.microsoft.com/mi...-and-meltdown-mitigations-on-windows-systems/

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Jsssssssss · May 30, 2019

Meltdown and Spectre

I suggest to do some reading...

See for example the below articles which include lots of links/infos:

How to Check and Update Windows Systems for the Meltdown and Spectre CPU Flaws
(article includes: "This
Google Docs file contains a list of the responses from some AV companies.")

Windows, Meltdown and Spectre: Keep calm and carry on

Windows 10: How do I disable all the Spectre and Meltdown mitigations in Windows 10 1903?

How do I disable all the Spectre and Meltdown mitigations in Windows 10 1903?

How do I disable all the Spectre and Meltdown mitigations in Windows 10 1903?

How do I disable all the Spectre and Meltdown mitigations in Windows 10 1903?

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