Upcoming Windows patch expected to slow Intel CPUs

Floating Cloud

Space Marshal
Apr 8, 2016
565
1,720
2,510
RSI Handle
Floating_Cloud
https://www.google.co.uk/amp/s/www.theregister.co.uk/AMP/2018/01/02/intel_cpu_design_flaw/#ampshare=https://www.theregister.co.uk/2018/01/02/intel_cpu_design_flaw/

This sucks, and is going to be big news I would imagine. Newer Intel CPU have features that will reduce the performance impact, so hopefully not too severe for at least some Intel users (I am running a third gen CPU so no chance for me).

The effect depends on the process involved and CPU in the system, but the quouted performance impact seen was between 5 and 30%.

No point worrying before we get more info though, so just FYI.
 

Radegast74

Space Marshal
Oct 8, 2016
3,000
10,655
2,900
RSI Handle
Radegast74
I was curious where the acronym FUCKWIT came from, so I googled a bit and found this...sigh, after that and UASS, Kernel Page Table Isolation seems so...wimpy.

from:
https://lwn.net/Articles/740608/

2) Namespace

Several people including Linus requested to change the KAISER name.

We came up with a list of technically correct acronyms:

User Address Space Separation, prefix uass_

Forcefully Unmap Complete Kernel With Interrupt Trampolines, prefix fuckwit_

but we are politically correct people so we settled for

Kernel Page Table Isolation, prefix kpti_

Linus, your call :)
 

BUTUZ

Space Marshal
Donor
Apr 8, 2016
3,411
11,411
2,850
RSI Handle
BUTUZ

rogesh

Space Marshal
Oct 25, 2014
624
1,178
2,500
RSI Handle
rogesh
What i read so far.
The fix will not affect the normal user experience. (+-2%).
Only processes which require a high virtualization like cloud computer (aws) will be heavily affected. So it might affect SC but there's nothing you can do bout it.
Aren't AMD CPUs better suited for servers? Heard such things on forums don't know if it's true tough
 

RoughGalaxy

Commander
Nov 2, 2017
74
372
100
RSI Handle
RoughGalaxy
intel is generally better at dedicated performance. It'll do gaming great, it'll do server hosting, it'll do streaming to twitch. From what I understand AMD is moderately more efficient at doing multiple things (like playing a game AND streaming it from the same machine)
 

mindfart

Space Marshal
Donor
Feb 10, 2015
585
1,785
2,610
RSI Handle
mindfart
intel is generally better at dedicated performance. It'll do gaming great, it'll do server hosting, it'll do streaming to twitch. From what I understand AMD is moderately more efficient at doing multiple things (like playing a game AND streaming it from the same machine)
I am a sysadmin.. but I have no clue about AMD in servers, because I have never seen it before. The reason they might do multitasking 'better' than intel ATM(on desktops), is because AMD is betting on lots and lots of cores.

AFAIK AMD CPU's run hotter, and use more energy than Intel CPU's, which in a datacenter is 4x cost(extra power, and extra heat coming into the DC which you have to put power in to remove)

But this upgrade will definitely hit companies like amazon, facebook, google and also smaller companies that are running everything within minimum ranges (ie. CPU utilization on 80%+). Just imagine.. you have 10k servers.. and your CPU's are being hit with a 5% performance decrease, and you want to keep the same threshold.. you will have to buy 500 machines to keep up..
 

HeadClot

Grand Admiral
May 29, 2014
197
671
1,210
RSI Handle
HeadClot88
AFAIK AMD CPU's run hotter, and use more energy than Intel CPU's, which in a datacenter is 4x cost(extra power, and extra heat coming into the DC which you have to put power in to remove)
This is true to a degree - The FX line that came before Ryzen ran hotter and used more power. Ryzen and Epyc server CPUs no longer do this due to the architecture.
 
  • Like
Reactions: mindfart

Floating Cloud

Space Marshal
Apr 8, 2016
565
1,720
2,510
RSI Handle
Floating_Cloud
So whilst this will definitely impact RSI and their hosting costs, it doesn't look like it will hit us at the game level (as per Michael's comment above). The Windows patches aren't out yet (as far as I know) but we've seen Linux kernel updates and this website has some game performance comparisons under Linux, which should reflect what we'll see with Windows too.

https://www.phoronix.com/scan.php?page=news_item&px=x86-PTI-Initial-Gaming-Tests

On a negative note, this is what RSI might be seeing with their AWS load (posted on Twitter by @timgostony 'Impact of the patch for the Intel bug on my AWS EC2 instances running Linux, a t1.micro and m3.medium. #KPTI '):



Which is either a 6% CPU usage jump, or 400% CPU usage jump, depending on how half-full/half-empty you want to be.

All good fun.
 
  • Like
Reactions: Bambooza
Forgot your password?