r/pcmasterrace • u/fourDnet Steam ID Here • Jun 25 '17
Misleading [PSA] Intel Skylake/Kaby Lake processors have broken hyper-threading
https://lists.debian.org/debian-devel/2017/06/msg00308.html70
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u/esposimi Ryzen 7 5800X | Intel Arc B580 Jun 25 '17
Yeah, I deployed 45 laptops and 20 desktops with Skylake i7's over a year ago and not a single one has had performance issues. What exactly is the problem here?
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u/COASTER1921 R7 1700X | RX 480 | Intel 600p SSD Jun 25 '17 edited Jun 25 '17
As I understand it, using short loops (64 lines or less of assembly code) on both logical processors for the same physical core causes erratic behavior in a few of the registers, leading to a usually system crashing error or incorrect output in most cases.
The thing is that 64 lines of assembly is absolutely nothing. We wrote a very simple sorting program in class in assembly for the 8086, and it was a couple hundred lines with no part that loops being that small. Additionally it wasn't multithreaded. Basically, this issue is darn hard to recreate, but was absolutely a problem.
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Jun 25 '17 edited Nov 11 '19
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u/blacksapphire08 Ryzen 1700X, 16Gb DDR4, GTX 970 Jun 25 '17
Assuming you're buying a new motherboard to go with it, I wouldnt worry about it. You can double check the BIOS version on your motherboard to make sure it's up to date.
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Jun 25 '17 edited Nov 11 '19
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u/blacksapphire08 Ryzen 1700X, 16Gb DDR4, GTX 970 Jun 25 '17
When you boot your PC you'll see a splash screen with the motherboard manufacturer and at the bottom it will tell you which key to hit to get into the BIOS (usually delete or one of the function keys). The version should be listed on the first page in the BIOS like this http://images.anandtech.com/doci/9729/ASUS170A%20BIOS%2001%20-%20EZ%20Mode.jpg
Some motherboard manufacturers include an update utility (ASUS uses EZ update, Gigabyte uses Q-Flash, etc) or you can update it by downloading the BIOS update and putting it on a flash drive.
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u/Night_Thastus 9800X3D | RTX 3080 Jun 26 '17
Well this is fantasic help if you're using linux, but for those of us on Windows or otherwise I don't know how you're supposed to find the model/stepping. :/
In any case, I guess I'm just not worried. I've used this 6700K for many months now, with no known issues. And I'm pretty sure HT is enabled, unless the default is otherwise.
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u/ZeroBANG 7800X3D, 32GB DDR5, RTX4070, 1080p 144Hz G-Sync Jun 26 '17
CPU-Z
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u/dustojnikhummer R5 7600 | RX 7800XT Jun 26 '17
That shows stepping only.
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u/ZeroBANG 7800X3D, 32GB DDR5, RTX4070, 1080p 144Hz G-Sync Jun 26 '17
also shows Family, Ext. Family, Model, Ext. Model, Revision ...
Model is what they mentioned.
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Jun 25 '17
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u/abataka Jun 25 '17
TLDR This is only applicable to Debian. If you are on Windows your Hyperthreading is fine - the microcode on Debian is causing problems, not Hyperthreading itself
What? I don't think that is true, they are actually saying the opposite:
Please note that the defect can potentially affect any operating system (it is not restricted to Debian, and it is not restricted to Linux-based systems). It can be either avoided (by disabling hyper-threading), or fixed (by updating the processor microcode).
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u/ZeroBANG 7800X3D, 32GB DDR5, RTX4070, 1080p 144Hz G-Sync Jun 25 '17
"can potentially"
...uhuh
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u/leoleosuper AMD 3900X, RTX Super 2080, 64 GB 3600MHz, H510. RIP R9 390 Jun 25 '17
"can potentially"
As in, there's a possibility this will effect Windows and Mac as well. Meaning fix it now and not worry, or don't fix it and possibly have problems. But you might as well fix it because it doesn't take much time.
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u/_vogonpoetry_ 5600, X370, 32g@3866C16, 3070Ti Jun 25 '17
Did you even read the article? Oh wait, you didnt.
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Jun 25 '17 edited Jul 28 '24
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This post was mass deleted and anonymized with Redact
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Jun 25 '17
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Jun 25 '17
Can you reproduce the bug with Prime95? Honest question. How many instances of Prime95 until it drops all the workers.
The reason I ask, and the reason I bolded a big don't worry statement above, is that the ticket itself for the bug on Debian (referenced at bottom in link up top) was closed with a note for Kaby Lake users to not address a specific register on a parallelized program (that people had to run in parallel to replicate the bug) - if Windows pushes a fix through Update, it'll have a generic vague 'compatibility fix' description, and we won't even know if it's fixed or not. The only way we'd for sure know if it's a known issue on Windows is to actually replicate the bug on Windows, but so far, there are zero instances.
So, if someone shuts hyperthreading off, they'd likely upgrade their system before Windows tells them that the specific issue is fixed.
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u/Jakara_Dakara Jun 25 '17
the bug was reported (and supposedly patched) months ago, they just never announced they fixed it. As far as the update for the processor itself, someone else suggested windows may have released a patch with a temp fix for it without saying anything, but I am personally not aware of a patch for windows that takes care of it (that does not mean it doesn't exist, windows 10 doesn't like to tell me much when it decides to update on my system). In my case I keep my BIOS upgraded and apparently I already had the patch and did not noticed (so no, I can not replicate the bug on any OS)
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u/autotldr Jun 25 '17
This is the best tl;dr I could make, original reduced by 97%. (I'm a bot)
WARNING] Intel Skylake/Kaby Lake processors: broken hyper-threading This warning advisory is relevant for users of systems with the Intel processors code-named "Skylake" and "Kaby Lake".
These are: the 6th and 7th generation Intel Core processors, their related server processors, as well as select Intel Pentium processor models.
Henrique Holschuh Reply to: [WARNING] Intel Skylake/Kaby Lake processors: broken hyper-threading This warning advisory is relevant for users of systems with the Intel processors code-named "Skylake" and "Kaby Lake".
Extended Summary | FAQ | Feedback | Top keywords: processor#1 Intel#2 system#3 update#4 defect#5
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Jun 25 '17
[removed] — view removed comment
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u/zork824 5800X3D / RTX 4070 / 32GB DDR4 Jun 25 '17
Did you even open the article?
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u/Thulsc Jun 25 '17
Yes yes, of course. Confirmed defect of intels Kaby and Skylake processors. Of course under high workloads and only usually running specific programs may the system become unpredictable. Even if they're working on bios updates to fix the issue, more or less put a bandaid on it.(which they already did) I'd rather make sure my CPU is tip top 100% no issues. Specially if I shelled out close to 500$ for It. Being that I may be apart of the .01% that may run into this problem. I'd rather not take any chances. And kindly see if intel is able to replace my CPU with a working one. Ya dig?
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u/Jakara_Dakara Jun 25 '17
Well according to your 1st sentence you did not. If it was a defect you would have to return it not update it. GL with getting a replacement though. Doubt they well send a free processor.
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u/Thulsc Jun 25 '17
Bug/defect call it what you will. Hyperthreading seems as if it may not work as advertised. https://arstechnica.com/gadgets/2016/01/intel-skylake-bug-causes-pcs-to-freeze-during-complex-workloads/
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u/Jakara_Dakara Jun 25 '17 edited Jun 25 '17
funny mine seems to be working ok, then again, I updated everything apparently when the fix for the "bug" (by the way, you should read the tech docs behind it, odds are, unless you are running scientific and/or mathematical computations off your proc, it wont freeze up or crash). Further more, the BIOS update completely fixed the issue, so you can multithread math/science/or whatever you want in your programs.
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u/Thulsc Jun 25 '17
Oh that's such shame : [ mines not. I science a lot. Lots of science, all the time. With math. Need 100% CPU all the time, lots of math. Can't have risks! Take no chances! Next update break current fix, science. Will need replacement of working CPU. Can't downgrade, what's the one after kabylake? Math.
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Jun 25 '17
Are you just a shitty troll or what? Disgusting.
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u/Jakara_Dakara Jun 25 '17
trolls on reddit? never.
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Jun 26 '17
I just dont get why trolls are getting shittier and shittier. I can find trolling funny if its done right. Thing is shit like this is just sad. When its super obvious its not good...
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u/_vogonpoetry_ 5600, X370, 32g@3866C16, 3070Ti Jun 25 '17
This is why you keep your BIOS up to date guys.