Microsoft released 1809 a little while ago and has decided to allow access to their new way to combat SPECTRE using Retpoline. Long story short, we all know that the SPECTRE microcode killed a lot of speed from many of our SSD/M.2s, for me it was up to 30+% on Q1 4k Read/write. By default, Microsoft has turned OF the Retpoline fix in build 1809 but you can manually turn it on if you wish. If not, Microsoft will roll out patches as they always do and eventually you'll get it. I wanted to see how much difference there actually was. Below is what I did and the results.
So I went back and turned off the Retpoline and took some reading and then turned it back on and tried again.
I'm definitely seeing some improvement, which is nice. When Spectre first came out I personally lost about 30-35% speed on my 4k Q1 random read/writes. Looks like the new Retpoline gets me back 4-7%. 4k Q32 raised by roughly a 100Mb/s which is also nice. Sequential read/write stayed the same, about 800mb/s slower than what it was originally. Overall I probably won't be able to tell the difference in real time but it is nice to see that Retpoline has some effect and I can actually see the changes through benchmarks.
I will put the steps of what I did. These are my steps as the "add reg" line shown in the microsoft article above, didn't work for me and kept coming up with a syntax error. For this to work you need to have installed Microsoft update: KB4482887
So I went directly into the registry.
1. Enter registry and save. (in case you mess up)
2. Navigated to HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management
3. Right clicked and ADD NEW DWORD (32BIT)
4. Renamed it to FeatureSettingsOverride
5. Double clicked the new registry entry and entered the hexidecimal value as 0x400
6. Right clicked and ADD NEW DWORD (32BIT)
7. Renamed it to FeatureSettingsOverrideMask
8. Double clicked the new registry entry and entered the hexidecimal value as 0x400
9. Restarted.
You can go to https://support.microsoft.com/en-us/...ngs-powershell in order to test it through powershell. Follow all the directions including the last to reset the values back to the originals after you get your read out. In the end you should see the following:
"BTIKernelImportOptimizationEnabled : True"
This will show that Retpoline is enabled. If at any time you have issues, restore your old registry. Once again this is how I did it. Your mileage may vary.
Pre-Retpoline
Post-Retpoline
So I went back and turned off the Retpoline and took some reading and then turned it back on and tried again.
I'm definitely seeing some improvement, which is nice. When Spectre first came out I personally lost about 30-35% speed on my 4k Q1 random read/writes. Looks like the new Retpoline gets me back 4-7%. 4k Q32 raised by roughly a 100Mb/s which is also nice. Sequential read/write stayed the same, about 800mb/s slower than what it was originally. Overall I probably won't be able to tell the difference in real time but it is nice to see that Retpoline has some effect and I can actually see the changes through benchmarks.
I will put the steps of what I did. These are my steps as the "add reg" line shown in the microsoft article above, didn't work for me and kept coming up with a syntax error. For this to work you need to have installed Microsoft update: KB4482887
So I went directly into the registry.
1. Enter registry and save. (in case you mess up)
2. Navigated to HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management
3. Right clicked and ADD NEW DWORD (32BIT)
4. Renamed it to FeatureSettingsOverride
5. Double clicked the new registry entry and entered the hexidecimal value as 0x400
6. Right clicked and ADD NEW DWORD (32BIT)
7. Renamed it to FeatureSettingsOverrideMask
8. Double clicked the new registry entry and entered the hexidecimal value as 0x400
9. Restarted.
You can go to https://support.microsoft.com/en-us/...ngs-powershell in order to test it through powershell. Follow all the directions including the last to reset the values back to the originals after you get your read out. In the end you should see the following:
"BTIKernelImportOptimizationEnabled : True"
This will show that Retpoline is enabled. If at any time you have issues, restore your old registry. Once again this is how I did it. Your mileage may vary.
Pre-Retpoline
Post-Retpoline
Brighttail wrote:
Microsoft released 1809 a little while ago and has decided to allow access to their new way to combat SPECTRE using Retpoline. Long story short, we all know that the SPECTRE microcode killed a lot of speed from many of our SSD/M.2s, for me it was up to 30+% on Q1 4k Read/write. By default, Microsoft has turned OF the Retpoline fix in build 1809 but you can manually turn it on if you wish. If not, Microsoft will roll out patches as they always do and eventually you'll get it. I wanted to see how much difference there actually was. Below is what I did and the results.
So I went back and turned off the Retpoline and took some reading and then turned it back on and tried again.
I'm definitely seeing some improvement, which is nice. When Spectre first came out I personally lost about 30-35% speed on my 4k Q1 random read/writes. Looks like the new Retpoline gets me back 4-7%. 4k Q32 raised by roughly a 100Mb/s which is also nice. Sequential read/write stayed the same, about 800mb/s slower than what it was originally. Overall I probably won't be able to tell the difference in real time but it is nice to see that Retpoline has some effect and I can actually see the changes through benchmarks.
I will put the steps of what I did. These are my steps as the "add reg" line shown in the microsoft article above, didn't work for me and kept coming up with a syntax error. For this to work you need to have installed Microsoft update: KB4482887
So I went directly into the registry.
1. Enter registry and save. (in case you mess up)
2. Navigated to HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management
3. Right clicked and ADD NEW DWORD (32BIT)
4. Renamed it to FeatureSettingsOverride
5. Double clicked the new registry entry and entered the hexidecimal value as 0x400
6. Right clicked and ADD NEW DWORD (32BIT)
7. Renamed it to FeatureSettingsOverrideMask
8. Double clicked the new registry entry and entered the hexidecimal value as 0x400
9. Restarted.
You can go to https://support.microsoft.com/en-us/...ngs-powershell in order to test it through powershell. Follow all the directions including the last to reset the values back to the originals after you get your read out. In the end you should see the following:
"BTIKernelImportOptimizationEnabled : True"
This will show that Retpoline is enabled. If at any time you have issues, restore your old registry. Once again this is how I did it. Your mileage may vary.
Pre-Retpoline
Post-Retpoline
Just loaded latest windows 10 updates which had a blurb about this topic. I think this is what you were referring to?
"Enables “Retpoline” by default if Spectre Variant 2 (CVE-2017-5715) is enabled."
May 14, 2019—KB4494441 (OS Build 17763.503)
https://support.microsoft.com/en-us/help/4494441/windows-10-update-kb4494441
