Microsoft Kernel Patch CPU Before and After Benchmarks Thread

By +Warwagon
in Microsoft (Windows)

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Radium

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Tasks such as calculating Pi shouldn't show any negative effects since calculating Pi doesn't require any system calls.

The performance hit comes from context switching which you essentially never do when you only calculate/estimate numbers.

Grand Master

adrynalyne

Posted
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  On 07/01/2018 at 01:14, LimeMaster said:

The patch seems a tad glitchy on older CPUs.

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What does that test even do? Performance is not hampered across the board. 

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LimeMaster

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  On 07/01/2018 at 02:03, adrynalyne said:

I’m sure, but what is it actually doing to test it?

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No clue. There doesn't seem to be documentation of what the tests entail.  Both tests (stress and bench) have similar results.

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adrynalyne

Posted
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  On 07/01/2018 at 02:16, LimeMaster said:

No clue. There doesn't seem to be documentation of what the tests entail.  Both tests (stress and bench) have similar results.

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If its just calculating pi, for example, the patch won't affect it at all.

Grand Master

LimeMaster

Posted
Posted
  On 07/01/2018 at 02:25, adrynalyne said:

If its just calculating pi, for example, the patch won't affect it at all.

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I figured the tests weren't exactly an accurate representation when comparing the results. It however did have a slight effect on the Multi Thread Ratio. It decreased after the patch was installed.

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neufuse Veteran

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It appears my SQL server 2017 benchmarks on windows actually saw a 2% performance increase after the patch :huh: In Linux SQL Server 2017 shows a 25% DECREASE in performance... ugh

 

SQL Server does a lot of IO and system calls.... doing mass IO bench marking should show any problems with this patch 

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Grand Master

LimeMaster

Posted
Posted
  On 07/01/2018 at 02:52, neufuse said:

It appears my SQL server 2017 benchmarks on windows actually saw a 2% performance increase after the patch :huh: In Linux SQL Server 2017 shows a 25% DECREASE in performance... ugh

 

SQL Server does a lot of IO and system calls.... doing mass IO bench marking should show any problems with this patch 

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I understand why Linus is angry then.

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adrynalyne

Posted
Posted
  On 07/01/2018 at 03:37, LimeMaster said:

I understand why Linus is angry then.

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So here is the thing--is he angry because he was unable to get performance better, vs. Windows?

Grand Master

LimeMaster

Posted
Posted
  On 07/01/2018 at 03:38, adrynalyne said:

So here is the thing--is he angry because he was unable to get performance better, vs. Windows?

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That would be my guess. Of course he blames Intel because everything was technically running smoothly beforehand.

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Yogurth

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Updated Techspot analysis and benchmarks. Up to 5% drop in overall performance aside from massive SSD slowdown. Still no Windows server workload tests apart from the Epic Games login server meltdown if that is a Windows server at all.

 

 

https://www.techspot.com/article/1556-meltdown-and-spectre-cpu-performance-windows/

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Mockingbird

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Posted (edited)
  On 07/01/2018 at 16:06, Yogurth said:

Updated Techspot analysis and benchmarks. Up to 5% drop in overall performance aside from massive SSD slowdown. Still no Windows server workload tests apart from the Epic Games login server meltdown if that is a Windows server at all.

 

 

https://www.techspot.com/article/1556-meltdown-and-spectre-cpu-performance-windows/

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That's without the microcode update.

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adrynalyne

Posted
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  On 07/01/2018 at 16:29, Mockingbird said:

That's without the microcode update.

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There hasn’t been enough testing with the microcode update to verify it. There is also a screenshot out there showing a massive performance hit after the meltdown patch on an AMD cpu. Just one that I saw. 

Grand Master

Mockingbird

Posted
Posted (edited)
  On 07/01/2018 at 16:33, adrynalyne said:

There is also a screenshot out there showing a massive performance hit after the meltdown patch on an AMD cpu. Just one that I saw. 

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...except that, on Windows, kernel VA shadow is off when using AMD processors.

 

Linux also disables kernel page-table isolation on AMD processors.

Grand Master

Yogurth

Posted
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  On 07/01/2018 at 16:29, Mockingbird said:

That's without the microcode update.

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Yup, this is Windows patch + BIOS update. The article is a work in progress and Techspot will update it when a new batch of patches arrives.

Grand Master

adrynalyne

Posted
Posted (edited)
  On 07/01/2018 at 16:37, Mockingbird said:

...except that, on Windows, kernel VA shadow is off when using AMD processors.

 

Linux also disables kernel page-table isolation on AMD processors.

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Show me where it is turned off and causing a performance hit please. The specific indicator if you don't mind.

 

 

Linux may disable kpti on AMD systems, but the NT kernel is not Linux.

 

Grand Master

Mockingbird

Posted
Posted
  On 07/01/2018 at 17:10, adrynalyne said:

Show me where it is turned off and causing a performance hit please. The specific indicator if you don't mind.

 

 

Linux may disable kpti on AMD systems, but the NT kernel is not Linux.

 

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It's turned off, so no performance impact.

 

PowerShell

 

Install-Module SpeculationControl

 

Set-ExecutionPolicy Bypass

 

Get-SpeculationControlSettings

Grand Master

adrynalyne

Posted
Posted (edited)
  On 07/01/2018 at 17:15, Mockingbird said:

It's turned off, so no performance impact.

 

PowerShell

 

Install-Module SpeculationControl

 

Set-ExecutionPolicy Bypass

 

Get-SpeculationControlSettings

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I'll wait for your results patiently. I've got mine here. I want to see where Windows turned off kernel va shadowing post patch.

Thats what you implied with what you said.

Grand Master

Mockingbird

Posted
Posted
  On 07/01/2018 at 17:22, adrynalyne said:

K.

 

Here is mine. Kernel VA shadowing was never enabled, even pre-patch.

 

Capture.PNG

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Which processor?

 

On Intel processors, Kernel VA shadowing is disabled if incompatible Anti-Virus is detected.

 

On AMD processors, Kernel VA shadowing is disabled.

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