Linux 4.14 Kernel Benchmarks With The Intel Core i9 7980XE

[phoronix]

Phoronix: Linux 4.14 Kernel Benchmarks With The Intel Core i9 7980XE

Following my Linux benchmarks of the newly-launched Core i9 7960X and Core i9 7980XE processors, here are benchmarks of the 18 core / 36 thread Extreme Edition processor when running on Linux 4.14...

http://www.phoronix.com/scan.php?page=news_item&px=Linux-4.14-i9-7980XE

[sdack]

Thanks for the PCID results.

Seems like AMD users don't need to worry about not having it.

[chuckula]

I had never even heard about this "PCID" conspiracy until it blew up and became this big deal about how RyZen/Threadripper/Epyc was being crippled under Linux for some reason.

It's too bad that Linux has no way for hardware vendors to make software updates that could support their hardware. I always knew Microsoft wouldn't let third parties work with Linux when Bill Gates developed it.

[NotMine999]

I had never even heard about this "PCID" conspiracy until it blew up and became this big deal about how RyZen/Threadripper/Epyc was being crippled under Linux for some reason.

It's too bad that Linux has no way for hardware vendors to make software updates that could support their hardware. I always knew Microsoft wouldn't let third parties work with Linux when Bill Gates developed it.

Where are you getting the idea that it's a "conspiracy" and then you conflate it with Ryzen, Threadripper, and Epyc?

From what I read at the following link, it looks like a "feature add" for "upcoming Intel CPUs"... to quote directly from Ingo's comments found at that link.

https://marc.info/?l=linux-kernel&m=150451753105925&w=2

[sdack]

Where are you getting the idea that it's a "conspiracy" and then you conflate it with Ryzen, Threadripper, and Epyc?

From what I read at the following link, it looks like a "feature add" for "upcoming Intel CPUs"... to quote directly from Ingo's comments found at that link.

https://marc.info/?l=linux-kernel&m=150451753105925&w=2

From what I've read so far is PCID supported on Intel CPUs back to Core i3 while on AMD CPUs it's not even available with the latest generation.

Early tests of 4.14 have shown some impressive performance improvements, but it wasn't clear where exactly these originated from. One text mentioned PCID boosting TLB performance, with a particular highly artificial benchmark showing a ~6x speed gain from it.

4.14 was announced as a release with some "very core new functionality" on some web sites, with PCID being one of these new features. The Phoronix benchmarks have sort of "debunked" any on-going speculations as to what the impact of PCID might be.

Imagine the consequences if PCID had shown a significant impact on application performance while it's not available on all CPUs. It would have created some chatter. Instead, now one might even want to disable it and only use it with applications where it's known to be beneficial.

But who knows... Perhaps it needs more work or requires other factors, but so far is there no further mystery regarding it's impact.

[xorbe]

Redis test:Set shows a notable perf regression with PCID

[sdack]

Redis test:Set shows a notable perf regression with PCID

Yes, and not a lot of improvement overall. But then again Apache static web page serving shows a 6.3% boost and that's still one of the most important applications of the World Wide Web today. So it's going to matter to some folks for sure (NGINX numbers would have been nice to know, too). Also Ebizzy shows a similar boost of 5.8%, being a web benchmark of sorts.

I'm going to conclude that PCID is an "Intel web server feature" for now, but I'm sure some people will dig deeper into it and find more uses for it eventually.

Only average Joe might be better advised to leave it off for now.