Benchmarking Retpoline Underflow Protection With Intel Skylake/Kabylake

[phoronix]

Phoronix: Benchmarking Retpoline Underflow Protection With Intel Skylake/Kabylake

Beyond the Retpoline support already found in the mainline Linux kernel, developers are working on Retpoline Underflow support that would be used for Intel Skylake and Kabylake CPUs. RETPOLINE_UNDERFLOW protects against falling back to a potentially poisoned indirect branch predictor when a return buffer underflows and this additional protection is needed for Intel Skylake/Kabylake processors. I ran a couple benchmarks...

http://www.phoronix.com/scan.php?page=news_item&px=Retpoline-Underflow-Benchmarks

[pete910]

File IO hit looks brutal !

[schmidtbag]

With performance losses like this, it makes me wonder if this puts the 1950X over the edge in terms of IPC vs the 7980X (non-E).

[caligula]

With performance losses like this, it makes me wonder if this puts the 1950X over the edge in terms of IPC vs the 7980X (non-E).

Intel fanboys won't buy AMD even if it was both faster and cheaper.

[Shooter8080]

Thanks for taking the time to put this together, very interesting.

However, I'm surprised you mentioned Skylake and Kabylake but didn't mention Coffeelake. Was that just an omission, or does Coffeelake not require the _underflow?

[andrebrait]

Intel fanboys won't buy AMD even if it was both faster and cheaper.

Like in the Athlon vs P3, Athlon XP vs P4 and Athlon 64 vs P4 days.

[bsp2020]

Intel fanboys won't buy AMD even if it was both faster and cheaper and more secure.

Fixed that for you.

[waxhead]

Intel fanboys won't buy AMD even if it was both faster and cheaper.

How about trowing stability in that sentence and see if you can still justify your point of view. I have not touched an AMD machine in over ten years so things may have changed, but I have never had any issues with a Intel CPU that was not mistreated by overclocking. AMD on the other hand have been troublesome for me in the past.

[caligula]

How about trowing stability in that sentence and see if you can still justify your point of view. I have not touched an AMD machine in over ten years so things may have changed, but I have never had any issues with a Intel CPU that was not mistreated by overclocking. AMD on the other hand have been troublesome for me in the past.

Probably true for those who overclock, but I've experience with Ryzens and 4-core Phenom. Both are rock stable with long uptime. I haven't tried overclocking.