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Discussion Starter #1
The gist is two issues.
  • Microsoft's thread scheduler incorrectly schedules jobs to partially busy cores when main cores are available. In other words, it doesn't properly differentiate between hyperthreaded vs underutilized main cores.
  • They also miscalculate how much cache is available for each thread.
It's unknown when these issues will be patched and how much Ryzen performance will be improved once a fix is in place.

I'm baffled that AMD and Microsoft were not working together months in advance on proper integration into their main OS but here we are. *queues conspiracy music*
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This might also explain why disabling SMT in some of the benchmarks, improved performance.

http://wccftech.com/amd-ryzen-performance-negatively-affected-windows-10-scheduler-bug/
 

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Quote:
Originally Posted by solar0987 View Post

lol it's always someone elses fault.. bullldozer all over again..
Except Ryzen can keep up with Intel's $1000 CPU but I suppose we'll just ignore that fact right now...
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Iconoclast
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Reviews should show out-of-box performance and then performance with manual affinities for everything, so an idea of the practical differences can be seen.
 

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Discussion Starter #5
Quote:
Originally Posted by solar0987 View Post

lol it's always someone elses fault.. bullldozer all over again..
Move along troll. This is nothing like Bulldozer.
 

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Quote:
Originally Posted by solar0987 View Post

lol it's always someone elses fault.. bullldozer all over again..
Then what explains Zen having same scores as 6900k in multithreading workloads, and same single threaded scores in Cinebench then, but this doesn't apply to gaming?

it's gaming software and Windows 10 that's the issue. Zen itself is great, it has the Broadwell-E or slighty better IPC, the software needs to be optimized to Zen.
 

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Quote:
Originally Posted by solar0987 View Post

lol it's always someone elses fault.. bullldozer all over again..
If you are going to be an obvious troll at least have the guts not to post and run.
 

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So will this fix also improve performance on INTEL products?
Quote:
In other words, it doesn't properly differentiate between hyperthreaded vs underutilized main cores.
 

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FOCAL ARIA FTW
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Quote:
Originally Posted by StrikerX View Post

Pretty sure it already is optimal on Intel
I would like to see proof of that if possible when AMD gets their fix. Maybe INTEL gets a bit of boost
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!

This quote alone is not enough for me to take 100% that the scheduler is optimal for INTEL. .
Quote:
Windows 10′ scheduler correctly identifies Intel's hyper-threads as lesser performing than principal core threads and schedules tasks in a way that's takes advantage of the additional throughput without negatively impacting performance. Unfortunately the scheduler currently is not able to differentiate principal core threads from virtual SMT threads with Ryzen and in fact sees 16 thread Ryzen 7 processors as processors with 16 physical cores with equal resources per thread.
 

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Quote:
Originally Posted by Wishmaker View Post

I would like to see proof of that if possible when AMD gets their fix. Maybe INTEL gets a bit of boost
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!

This quote alone is not enough for me to take 100% that the scheduler is optimal for INTEL. .
Quote:
Windows 10′s scheduler correctly identifies Intel's hyper-threads as lesser performing than principal core threads and schedules tasks in a way that's takes advantage of the additional throughput without negatively impacting performance. Unfortunately the scheduler currently is not able to differentiate principal core threads from virtual SMT threads with Ryzen and in fact sees 16 thread Ryzen 7 processors as processors with 16 physical cores with equal resources per thread.
Dude can you read? The answer to your question is literally the first sentence in the quote you provided. I've bolded it for you, for emphasis. Whether you choose to believe it or not is on you, but Win10 already knows the difference between a thread and a true core for Intel CPUs.
 

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Iconoclast
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Any forthcoming fix isn't likely to benefit Intel., but WCCF's explanation is a shoddy one..."hyper-threads" and "principal core threads" are a false dichotomy. Within one core, there is no difference between logical cores, you just can't use them both at the same time if you want one to run at full speed.

SMT/HT let one physical core present itself as two logical cores. Windows is aware of the topology of Intel CPUs and generally schedules to every other logical core first, before scheduling to logical cores that execute on the same physical core. Windows 10 is not yet aware of Ryzen's topology, so can't take SMT or the different CCXes into account.
 

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Discussion Starter #13
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Reactions: Blameless

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All I can add is that Win10 worked a lot better on my A10-7700k than Win7 did in some benchmarks. I chalked it up to the scheduler handling CMT better under Win10. MS had years to sort out that problem.

We'll see if MS can help people squeeze out any more performance with scheduler improvements. In the meantime, Zen users can probably help themselves by running higher RAM speeds wherever possible.
 

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Quote:
Originally Posted by Castaa View Post

Update from AMD: Scheduler working as intended.

https://community.amd.com/community/gaming/blog/2017/03/13/amd-ryzen-community-update?sf62107357=1
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So wait, but Zen works better under win7 than Win10 scheduler-wise.

So, i have to assume AMD doesn't want to tick off Microsoft for their close partnership, especially on consoles.

And, it is easier on AMD to work with game developers to optimize for Ryzen directly than make Microsoft look bad to the public by making them admit their scheduler is unoptimial for Ryzen.
 

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Quote:
Originally Posted by ChronoBodi View Post

So wait, but Zen works better under win7 than Win10 scheduler-wise.

So, i have to assume AMD doesn't want to tick off Microsoft for their close partnership, especially on consoles.

And, it is easier on AMD to work with game developers to optimize for Ryzen directly than make Microsoft look bad to the public by making them admit their scheduler is unoptimial for Ryzen.
i can't think why there is a Win7/10 difference, tbh that would be over my head. but i don't recall AMD hesitating to point the finger at MS over bulldozer. nor do i recall there being any bad blood over it; MS happily complied.

and i think consoles are mutually beneficial for both; it does bring in revenue which at times kept AMD from bleeding to death, but i don't think MS would be able to find another vendor w/o substantially increasing the cost.

when all said and done, w/o looking too deep into it, why would MS get upset if AMD needed to ask for help?

and i am specifically mentioning help in a corporate PC manner to not hurt feelings, just not making a statement blaming MS.
 

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This performance issue isn't just with AMD.
My i7-3770k sees up to about 75% more performance on windows 7 with things like streaming, rendering graphics and video, along with some other heavy cpu bound tasks.
I'd love to use windows 10, but that drastic performance dip is just not something i can live with.

this extends to every computer i've tried windows 10 on, most of it is older hardware, but even a new i5 gaming laptop i got my daughter, runs better under win7 than it does in 10.

Benchmarking software seems to run better numbers in 10, but real world applications, no.
 
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