Bisected: The Unfortunate Reason Linux 4.20 Is Running Slower

[schmidtbag]

What I find confusing is why is this happening now? And is Windows affected by this?

Intel may have already answered that question internally. Remember the recent chip marketing that only mentioned number of cores, no mention of threads or HT....

I was just about to say the same thing.

[perpetually high]

It was only three days ago that researchers announced 7 more attacks. Didn't see it covered here this week.

Spectre, Meltdown researchers unveil 7 more speculative execution attacks: https://arstechnica.com/gadgets/2018...ution-attacks/

[Michael]

It was only three days ago that researchers announced 7 more attacks. Didn't see it covered here.

https://arstechnica.com/gadgets/2018...ution-attacks/

That's because according to Intel, the current mitigations already cover these new attack vectors.

[Venemo]

This is getting out of hand... are we seriously sacrificing 20% performance for this nonsense?

Michael Perhaps you could please update the article with some info on how to disable all these mitigations? For those of us who feel secure without them.

[perpetually high]

That's because according to Intel, the current mitigations already cover these new attack vectors.

I see, thanks for clearing that up.

[Guest]

Michael - Any chance you could do a pre-Spectre/Meltdown kernel to current kernel (with all of the spectre/meltdown mitigations that are enabled by default) performance comaparison?

[Michael]

Michael - Any chance you could do a pre-Spectre/Meltdown kernel to current kernel (with all of the spectre/meltdown mitigations that are enabled by default) performance comaparison?

Yes already plan to as soon as time allows.

[Dedale]

Is there a Godwin point variant for DE holy wars?

I dunno... Maybe mentioning Outreachy ?

More seriously, it is in line with the gossip i gathered before when predictions about the performance cost of mitigation measures. This suggests that hardware fixes may be worth it.

Thank you Michael for the work and double thank you for being so fast.

[ms178]

2018 turns out to be a very bad year for Intel CPU owners (especially pre-Haswell, myself included). And there is still more research on the way which might lead to even worse performance. My god, they should be forced to sell their CPUs with red warning stickers only...

[ms178]

Yes already plan to as soon as time allows.

As there is the option to disable these mitigations via the boot command line, also having a 4.20 with/without mitigations enabled comparison would be welcome (on older and newer Intel CPUs but also selected AMD CPUs for comparison and relative to the stock 4.20 configuration).