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Haswell

Intel chip flaw forces OS kernel redesign - 5-30% performance loss predicted

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https://www.theregister.co.uk/2018/01/02/intel_cpu_design_flaw/

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A fundamental design flaw in Intel's processor chips has forced a significant redesign of the Linux and Windows kernels to defang the chip-level security bug.

Programmers are scrambling to overhaul the open-source Linux kernel's virtual memory system. Meanwhile, Microsoft is expected to publicly introduce the necessary changes to its Windows operating system in an upcoming Patch Tuesday: these changes were seeded to beta testers running fast-ring Windows Insider builds in November and December.

Crucially, these updates to both Linux and Windows will incur a performance hit on Intel products. The effects are still being benchmarked, however we're looking at a ballpark figure of five to 30 per cent slow down, depending on the task and the processor model. More recent Intel chips have features – such as PCID – to reduce the performance hit. Your mileage may vary.

Similar operating systems, such as Apple's 64-bit macOS, will also need to be updated – the flaw is in the Intel x86-64 hardware, and it appears a microcode update can't address it. It has to be fixed in software at the OS level, or go buy a new processor without the design blunder.

More technical stuff:
http://pythonsweetness.tumblr.com/post/169166980422/the-mysterious-case-of-the-linux-page-table
https://news.ycombinator.com/item?id=16046636
Summary of attack vector https://news.ycombinator.com/item?id=16001476

AMD chips seem unaffected https://lkml.org/lkml/2017/12/27/2

@Folterknecht @OOPMan

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Is this a straight potential 30% hit to everyday users (gaming etc), or something that won't be that noticeable?  

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1 hour ago, cavman276 said:

Is this a straight potential 30% hit to everyday users (gaming etc), or something that won't be that noticeable?  

Oh, you'll probably notice it since this has to do with memory addressing

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53 minutes ago, Fulcrous said:

Yeah, PCGamer said the same is expected with Windows.

It seems this issue mostly relates to systems run multiple OSes at once, such as cloud compute hardware nodes.

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As I understand it, the issue is VM related (one VM having access to an other "independent" VM). 

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https://github.com/torvalds/linux/commit/00a5ae218d57741088068799b810416ac249a9ce

Quote
   - Exclude AMD from the PTI enforcement. Not necessarily a fix, but if
     AMD is so confident that they are not affected, then we should not
     burden users with the overhead"

Looks like AMD users (for Linux) are in the clear for now.

 

13 hours ago, Fulcrous said:

NO hits to gaming/regular perf as expected.

https://www.computerbase.de/2018-01/intel-cpu-pti-sicherheitsluecke/

One bench is fairly insignificant, need more data for CPU bottlenecks. BUT I think it wouldn't be that bad, or even noticeable to the unaware masses.

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Wew, and I wanted intel for my next rig. Guess I'm cured of that. :doge: Also: some people went ahead with updating their windowses to get some ban-aid for this issue and get into trouble when running amd. Or so I've heard.

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4 hours ago, orzel286 said:

Wew, and I wanted intel for my next rig. Guess I'm cured of that. :doge:

Don't forget that while Meltdown mostly affects Intel, Spectre is a problem for AMD and ARM too.

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On 1/4/2018 at 2:41 AM, Haswell said:

Looks like AMD users (for Linux) are in the clear for now.

The pre Ryzen AMD CPUs are still vulnerable to Spectre.  SOme of them may be vulnerable to Meltdown.  I've seen conflicting info on that.

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https://cloudblogs.microsoft.com/microsoftsecure/2018/01/09/understanding-the-performance-impact-of-spectre-and-meltdown-mitigations-on-windows-systems/

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  • With Windows 10 on newer silicon (2016-era PCs with Skylake, Kabylake or newer CPU), benchmarks show single-digit slowdowns, but we don’t expect most users to notice a change because these percentages are reflected in milliseconds.
  • With Windows 10 on older silicon (2015-era PCs with Haswell or older CPU), some benchmarks show more significant slowdowns, and we expect that some users will notice a decrease in system performance.
  • With Windows 8 and Windows 7 on older silicon (2015-era PCs with Haswell or older CPU), we expect most users to notice a decrease in system performance.
  • Windows Server on any silicon, especially in any IO-intensive application, shows a more significant performance impact when you enable the mitigations to isolate untrusted code within a Windows Server instance. This is why you want to be careful to evaluate the risk of untrusted code for each Windows Server instance, and balance the security versus performance tradeoff for your environment.

Much rip for old chips.

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rip my PC. Looks like when I upgrade it will have to be CPU, GPU, PSU and SSD.

 

FML

 

Now that brings up the question, what CPU? 

 

reading through it, looks like the spectre fixes are causing the performance drop so does that mean older AMD cards are rip too? 

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13 hours ago, MagicalFlyingFox said:

rip my PC. Looks like when I upgrade it will have to be CPU, GPU, PSU and SSD.

 

FML

 

Now that brings up the question, what CPU? 

 

reading through it, looks like the spectre fixes are causing the performance drop so does that mean older AMD cards are rip too? 

In hindsight I'm happy that I waited with Coffeellake (first wanted to see Z390) and instead switched from 3570K to 3770K. I 'll lean back and wait for new CPUs to be released.

The question is when these fixes will be implemented in hardware. Zen+ (spring '18) won't have them I'm pretty sure.

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16 hours ago, MagicalFlyingFox said:

rip my PC. Looks like when I upgrade it will have to be CPU, GPU, PSU and SSD.

 

FML

 

Now that brings up the question, what CPU? 

 

reading through it, looks like the spectre fixes are causing the performance drop so does that mean older AMD cards are rip too? 

Why? Not like you running VMs and stuff, impact will (is) marginal. 

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