KPTI + Retpoline Linux Benchmarking On Old Laptops

[dungeon]

At least Raspberry Pi and Commodore 64 are not affected by M/S

This is why at my company private devices are prohibited and reason to get fired.

Likely there are companies when even private underwear is also prohibited

[Kemosabe]

Guys,
Maybe this is a silly question and already have been answered, but is it possible to turn off this feature from BIOS (and in Kernel) and be happy without all these regressions?

This is why at my company private devices are prohibited and reason to get fired.

[dyfrgi]

Thanks for the new numbers! I would love to see some more numbers on old hardware with IBRS enabled, as it is by default in Redhat's kernels today. In my own tests, I've seen slowdowns by as much as 8x on a trivial fibonacci computation (6-instruction kernel), and about 2x on FFMPEG. Those are on an E5-2660 v3. I haven't seen any of those here yet, though I did find a couple on openbenchmarking.org. Any chance you'll do an article with that? I think the huge impact is very compelling.

[Michael]

Guys,
Maybe this is a silly question and already have been answered, but is it possible to turn off this feature from BIOS (and in Kernel) and be happy without all these regressions?

It's been covered in other articles but you can simply boot your kernel with: noretpoline kpti=off

[smartalgorithm]

Guys,
Maybe this is a silly question and already have been answered, but is it possible to turn off this feature from BIOS (and in Kernel) and be happy without all these regressions?

[phoronix]

Phoronix: KPTI + Retpoline Linux Benchmarking On Old Laptops

Over the past week and a half of running many benchmarks looking at the performance impact of the Linux KPTI and Retpoline patches for Spectre and Meltdown mitigation, one of the most common test requests is some thorough benchmarks on older systems. Why that's important is with older (pre-Westmere) CPUs there isn't PCID (Process Context Identifier) support that's used by KPTI, which helps offset some of the performance loss. So for some test results to share today are two old ThinkPads from the Clarksfield and Penryn days compared to a newer Broadwell ThinkPad in looking at the performance difference.

http://www.phoronix.com/vr.php?view=25833