Thursday, May 16th 2019

Apple: Protecting Macs from MDS Vulnerabilities May Reduce Performance by up to 40%

Apple has advised users that they should disable Intel's Hyper-Threading feature on the company's computers due to the recently exposed MDS vulnerabilities. Citing internal testing, Apple said that users can expect an up to 40% performance loss in such a scenario (depending on system and workload, naturally) in various benchmarks and multithreaded workloads. The performance loss is understandable - you're essentially halving the number of threads available for your CPU to process data.

Like Intel said, it becomes an issue of how much users value their performance compared to the security risks involved: a classic risk/benefit scenario, which shouldn't ever be in the equation, after all. If users buy a system with a CPU that has known performance levels, they will obviously expect those to be valid for the longevity of the product, unless otherwise stated and considering operational variances that fall within a margin of error/product obsolescence. Halving your performance because of a design flaw that resulted from an effort to achieve higher and higher IPC increases doesn't strike as a way to inspire confidence in your products.
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23 Comments on Apple: Protecting Macs from MDS Vulnerabilities May Reduce Performance by up to 40%

#2
Vayra86
I really wonder how big this is going to get.
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#3
moproblems99
Honestly, this will hurt MacBooks the most because they don't have that many cores to begin with...

Vayra86, post: 4048502, member: 152404"
I really wonder how big this is going to get.
Just remember, this doesn't effect end users /s
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#4
Penev91
The best news for Apple in a long time. This only means that their users will be forced to upgrade next year.
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#5
newtekie1
Semi-Retired Folder
Well lets face it, Mac users don't buy the computers for the performance anyway...
Posted on Reply
#6
Static~Charge
moproblems99, post: 4048508, member: 155919"
Honestly, this will hurt MacBooks the most because they don't have that many cores to begin with...
True. Far too many of the so-called "Core i7 Mobile" processors are actually 2 cores, 4 threads. That's a Core i3 in my book....
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#7
Shihabyooo
newtekie1, post: 4048530, member: 20670"
Well lets face it, Mac users don't buy the computers for the performance anyway...
Weren't Macs popular among the media/content creation communities?
Posted on Reply
#8
yakk
I guess that means Apple's arm cpu is up to 40% more competitive now... ;)
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#9
Vya Domus
Shihabyooo, post: 4048584, member: 91709"
Weren't Macs popular among the media/content creation communities?
Because of the few software pieces that are exclusive to MacOS, certainly not because of the performance.
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#10
phanbuey
Shihabyooo, post: 4048584, member: 91709"
Weren't Macs popular among the media/content creation communities?
Ages ago -

Still, no one says you can't put your render farm on a subnet, NAT it to the internet for updates only, and not give anything on the outside direct access to it.

But yeah... them javascripts and leaky processors. Might go AMD this next round, but as soon as I do there will security flaws exposed there so meh...
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#11
OSdevr
Macs aren't exactly secure to begin with, or high performance.
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#12
danbert2000
If Apple leaves this as an advisory and doesn't take the step of disabling HT by default, then they are essentially covering their asses. They just want to be off the hook if you use a Mac and end up getting exploited by MDS, even though that is probably very unlikely. MDS is going to be a big deal for servers with multiple companies using VMs on the same chip. For personal use I'm guessing this is about as bad as any other attack vector. If you're owned (someone is able to get a virus on your machine to exploit MDS), then you're going to have an issue with that before it even gets to the processor-specific exploit.
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#13
Imsochobo
Static~Charge, post: 4048536, member: 61342"
True. Far too many of the so-called "Core i7 Mobile" processors are actually 2 cores, 4 threads. That's a Core i3 in my book....
Yeah, it depends on screen size / platform what an i7 is, sometimes dual core, sometimes 6 core....
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#14
Crackong
Patch notes:

Fixed the bug that "old generation CPUs being too powerful it affects the sales of new machines"
Adjusted CPU performance like we did on battery performance for a better user experience.
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#15
ssdpro
"If users buy a system with a CPU that has known performance levels, they will obviously expect those to be valid for the longevity of the product, unless otherwise stated and considering operational variances that fall within a margin of error/product obsolescence. Halving your performance because of a design flaw that resulted from an effort to achieve higher and higher IPC increases doesn't strike as a way to inspire confidence in your products."

The problem is there is no legal remedy. If a decision or statute existed, most cars on the market today would be exposed as long term fuel economy even performance drop due to direct injection carbon build up on intake valves. Vacuum cleaners would be vulnerable as they slowly clog over time. Keurig coffee makers clog over time. There is a magical belief a processor should perform like new for the life of the product. It is a consumer product just like the products above. Hence, consumable and by statute degrades with time. The only legal remedy to this stuff is if Intel willingly knew about it and, if asked, didn't disclose or conspired to withhold the info. Nothing requires them to disclose voluntarily even if they knew.
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#17
NC37
Penev91, post: 4048517, member: 185017"
The best news for Apple in a long time. This only means that their users will be forced to upgrade next year.
:clap:
Posted on Reply
#18
Caring1
ssdpro, post: 4048790, member: 131037"
The problem is there is no legal remedy. If a decision or statute existed, most cars on the market today would be exposed as long term fuel economy even performance drop due to direct injection carbon build up on intake valves. Vacuum cleaners would be vulnerable as they slowly clog over time. Keurig coffee makers clog over time. There is a magical belief a processor should perform like new for the life of the product. It is a consumer product just like the products above. Hence, consumable and by statute degrades with time. The only legal remedy to this stuff is if Intel willingly knew about it and, if asked, didn't disclose or conspired to withhold the info. Nothing requires them to disclose voluntarily even if they knew.
You're talking about normal wear and tear and degradation.
Not flaws that affect performance.
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#19
HwGeek
Static~Charge, post: 4048536, member: 61342"
True. Far too many of the so-called "Core i7 Mobile" processors are actually 2 cores, 4 threads. That's a Core i3 in my book....
Poor Apple "i7" 2C/4T Macbook Owners- they just got downgraded to "Pentium" with HT OFF.... no Wait, Pentiums got HT now, so let's say Celeron!.
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#20
R-T-B
HisDivineOrder, post: 4048792, member: 136874"
Lawsuits seem inevitable.
I'd be genuinely surprised if one is not filed. I'd be more surprised if one succeeds though.
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#21
medi01
Shihabyooo, post: 4048584, member: 91709"
Weren't Macs popular among the media/content creation communities?
Yeah, but because fasion/"it has color calibration built into OS", definitely not performance.
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#22
ScaLibBDP
>>...
>>The performance loss is understandable - you're essentially halving the number of threads
>>available for your CPU to process data.
>>...

This is Not right.

I'm a C/C++ Software Engineer and I've been using Intel HTT since 2007 year. In a period from 2007 until 2014 on different R&D projects and since 2014 until now on production quality HPC projects. So, when Intel HTT is disabled number of Logical CPUs equals to number of Physical Cores of a CPU. Depending on an Intel architecture when Intel HTT is enabled it increases number of Logical CPUs. For mainstream architectures by 2x, for KNL architecture by 4x. When Intel HTT is disabled a Processing Power ( PP ) of an HPC-like application with correct threads management is The Same! Period! This is because PP is a function of Physical Cores and is Not a function of Logical Cores.

I think Apple Corporation is talking about UI-like application and these applications never do correct thread management similar to what is done in HPC-like applications. If you ever worked with ESRI ( geoinformatics ) or AGI ( aerospace ) software you will understand what I'm talking about.

Processing Power ( PP ) of a CPU is calculated as follows:

Base Clock in GHz * Number of Physical Cores * Number of SP/DP elements per vector * Number of FP ops per Clock

For example, for Intel Core i9-9900K:

3.6 GHz * 8 * 16 * 2 = 921.6 GFLOPs

and it will be 921.6 GFLOPs regardless state of Intel HTT!

Search the Web with a Tag "Intel Hyper-Threading Technology and Processing Power of a Computer System"
Posted on Reply
#23
R-T-B
You're a C++ developer and you don't understand why "barrel processor" style features like hyperthreading increases throughput in general computing? And his statement IS correct... you know what a thread vs a core is, don't you? Meh. I guess this is more an architectural thing anyways.
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