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Comment by pabs3 | Hacker News Reader

At least based on my tests it is not possible to remove the impact of the mitigations with boot-time flags: this "disabled" the mitigations but the code paths for eg for kernel calls is still much different and slower than pre-mitigation kernels. Pre-mitigation I measured just over 100 ns for a bare do-nothing system call, while after it is over 1,000. However if you disable mitigations on the boot command line I still see over 500 ns so it is not close to the old performance.

You'd have to run an old kernel to really get pre-mitigation performance. I tested this just after Meltdown + Spectre 1-3, so things may have better or worse since then, I'm not sure.

That's why average joe doesn't like Linux. how i'm going to use this?

https://wiki.ubuntu.com/Kernel/KernelBootParameters

You must put it on kernel options, somewhere on grub config files.

The "average joe" shouldn't be doing this.

> That's why average joe doesn't like Linux

Having seen the attempts at making Linux friendly for theoretical frictionless spherical Joes in vacuum, I'd rather just have my 1-2% market share GNU/Linux OS for unix greybeards, warts and all. The friendly GUI shell on top of Linux for average Joes is called Chrome OS and Android.

In 5.2 (next major release) the "mitigations=off" flag should cover it all. Up until recently there wasn't really a need for such a catch-all so it hadn't been made.

Maybe you'll prefer the Windows version:

  reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management" /v FeatureSettingsOverride /t REG_DWORD /d 3 /f

  reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management" /v FeatureSettingsOverrideMask /t REG_DWORD /d 3 /f

Clearly windows is never going to be ready for the desktop.

Haha! Made my day.

Source for this is here [1].

[1]: https://support.microsoft.com/en-us/help/4072698/windows-ser...

Absolutely. I was talking to an average joe the other day and he was complaining how hard it was to roll back Spectre, Meltdown, and ZombieLoad mitigations to improve his compilation speed.

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