Wednesday, October 6th 2021

AMD Processors Lose 15% Gaming Performance with Windows 11, L3 Cache Latency Tripled

Apparently, AMD processors officially compatible with Windows 11, exhibit a three-times increase in L3 cache latency with the new operating system. The new operating system is also found to break the "preferred cores" system on AMD processors (UEFI CPPC2), in which the two "best" CPU cores, which can sustain the highest boost frequencies, are highlighted to the operating system, so most of the light-threaded traffic could be sent to them.

AMD and Microsoft jointly made this discovery, and listed out potential impact on application performance. The increased L3 cache latency affects performance of applications sensitive to memory performance. They also warn of a 10-15% loss in gaming performance. On the other hand, a dysfunctional "preferred cores" system would mean reduced performance in light-threaded tasks as the OS is unaware which are the processor's two best cores. Thankfully, both issues can be fixed via software updates, and AMD is working with Microsoft to push fixes for both issues through Windows Update, in an update rollout scheduled within October 2021.
Source: AMD
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141 Comments on AMD Processors Lose 15% Gaming Performance with Windows 11, L3 Cache Latency Tripled

#26
mouacyk
TheLostSwedeHang on, wasn't Windows 11 tested by expert users, so we wouldn't have problems like this?

Also, some network cards are apparently having issues, specifically Intel's Killer NICs, which is a bit ironic...
Yes, the experts in making money for themselves/M$.
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#27
ppn
First 25% on the GPU. now 15% penalty, I guess we have to wait for a new hardware fix to be able to quickly do the sandbox thing.
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#28
Tomorrow
ManofGodBecause of recent history and commonsense because, even if I am wrong, it is not that much of a leap. The fact that their XBox Systems have AMD does not stop Microsoft from being buddy buddy with Intel, nonetheless.
Also when threadripper 2000 series launched it took months for Microsoft to fix their scheduler. Linux was fine.
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#29
TheoneandonlyMrK
Yeah except it hit's Intel too in some circumstances, the FPS drop.
Likely to do with VMR (acronym might be VmS or something, no VBS read the thread) ie fully virtualized OS security.

There were reports it'll affect ALL CPUs as much as 25%.
Feels like Intel's pr mill utilised that info to nudge sales IMHO.

Ie bullshit news piece IMHO without context, testing and competitive comparison.

@btarunr you even linked OEM window 11 build advice?!.

Apparently your sources are shit and secret.
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#30
zlobby
windwhirlIf anything, I detected this months ago and made the corresponding report through Feedback Hub at the time
You're the expert user we need but we don't deserve. :D
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#31
john_
Oh, come on. Just put a "Sponsored by Intel" in Windows 11's boot screen.
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#32
windwhirl
TheoneandonlyMrKYeah except it hit's Intel too in some circumstances, the FPS drop.
Nope, that's a different issue. This concerns specifically L3 cache performance for AMD Processors and problems with the scheduler not assigning loads to the correct cores on AMD processors.
TheoneandonlyMrKThere were reports it'll affect ALL CPUs as much as 25%.
If you mean Hypervisor-Protected Code Integrity (HVCI), if you're running one of the supported processors, performance hit averages at 5%, with specific loads getting performance hits as high as 9% or as low as 0%

If you're running an unsupported processor, well, I don't know, but expect it to be worse.
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#33
theGryphon
Win 11 sounds like it's as half-baked as Win 8 was... maybe even worse.
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#34
Vayra86
mechtechWin 11………..Beta
Win.... now forever in beta

I'm keeping my strict policy of maximum delay on Windows updates. Should be all fine then...
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#35
Guwapo77
Looks like I made the right choice to wait this out. Anyone know when the Windows 11 SP1 disc will ship? :D
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#36
KarymidoN
What a Shocker!!! Another windows BUG that only affects AMD, reminds me of Early ZEN days... Lets just hope we get a fix ASAP, i've already noticed some lag on the OS (Running a 3700X + 32GB 2933mhz + 1070 OC + NVME SSD)
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#37
TheoneandonlyMrK
windwhirlNope, that's a different issue. This concerns specifically L3 cache performance for AMD Processors and problems with the scheduler not assigning loads to the correct cores on AMD processors.

If you mean Hypervisor-Protected Code Integrity (HVCI), if you're running one of the supported processors, performance hit averages at 5%, with specific loads getting performance hits as high as 9% or as low as 0%

If you're running an unsupported processor, well, I don't know, but expect it to be worse.
Fair enough, now about those source's, context ,competitive comparison?!.

Oh and I said VBS or corrected what I meant.

m.hexus.net/tech/news/software/148462-pc-users-need-wary-vbs-performance-impacts-win-11/

This makes VBS seem like the OS system level component of HVci

I'll await benches before I get critical, I'm not going 11 yet anyway.
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#38
AteXIleR
I don't see the benefit changing to 11, for now..
Its fomo is invalid, what would even be the advantage of the 'upgrade'?

The newer interface and the bloatware does not justify it in my mind.
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#39
windwhirl
TheoneandonlyMrKFair enough, now about those source's?!.

Oh and I said VBS or corrected what I meant.

m.hexus.net/tech/news/software/148462-pc-users-need-wary-vbs-performance-impacts-win-11/

This makes VBS seem like the OS system level component of HVci

I'll await benches before I get critical, I'm not going 11 yet anyway.
Ah, I posted that in another thread. Here you go:

www.tomshardware.com/news/windows-11-security-gaming-application-performance-benchmarks

Tom's Hardware's tested VBS on and off on Intel's 10700K and 11700K and AMD's 3800X and 5800X. Mind you, this are merely tests on VBS impact alone, it's got nothing on whatever is going on with the L3 cache issue.

The 15% impact is an AMD's estimated measure on select games
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#40
phanbuey
VBS alone gives me a pretty noticeable hit
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#41
TheoneandonlyMrK
windwhirlAh, I posted that in another thread. Here you go:

www.tomshardware.com/news/windows-11-security-gaming-application-performance-benchmarks

Tom's Hardware's tested VBS on and off on Intel's 10700K and 11700K and AMD's 3800X and 5800X. Mind you, this are merely tests on VBS impact alone, it's got nothing on whatever is going on with the L3 cache issue.

The 15% impact is an AMD's estimated measure on select games
"We found that the security mechanisms do reduce gaming performance, with the average impact on an 11th-gen Intel chip being in the 5% range (7% peak in one title). That may not seem like much to the untrained eye, but that's roughly an Intel CPU generation's worth of disappearing performance. We recorded a slightly smaller impact on AMD Ryzen systems, with a 4% average for a Ryzen 5000 chip (and an outlier 8% loss in one title).

That's what they said upto 7-8% with testing.

Plus AMD state 15% is possible while Intel stayed shtum and that all equals this, right I'll leave you to it I was mistaken, it's far less significant then I thought, at least ATM ,you can stay on 10, shrug.

@btarunr I feel the story could have been written better but ah well.
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#42
Math9999
I have Threadripper 3990X some of the benchmark in Windows 11 will not use all cores and threads of the 3990x as it was in Windows 10 for example V-Ray 5 Benchmark in Windows 11 use 64 threads only, in windows 10 it will users all 128threads. Also in Windows 11 I tested all NVME drives (8 drives m.2 pcie 4.0) with CrystalDiskMark and all drives in Windows 11 in write test part RND4KQ3216 are slower than Windows 10 by more than 300% (in Windows 10 it is 3500MB/s in Windows 11 850MB/s).
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#43
windwhirl
phanbueyVBS alone gives me a pretty noticeable hit
Intel is more affected by VBS than AMD, and you're on the 10th gen, which gets a bigger hit than 11th gen.
TheoneandonlyMrKit's far less significant then I thought
Yeah, though that left me hungry for information on 8th and 9th gen. 10th gen was hit harder than 11th gen, so I feel it's natural 9 and 8 are even worse off. But how much, I don't know.

And I don't know about Zen+ either, which doesn't have MBEC...
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#44
Tomgang
Looks like I should stay away from windows 11 for a while yet. I am not interested in losing 15 % performance from my amd CPU's.
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#45
Tigger
I'm the only one
Can we have a Intel/Microsoft conspiracy theory thread instead of crapping it all in here.
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#46
phanbuey
I mean AMD knows about it... MS knows about it...

Reality is MS loves AMD (Xbox is amd based), and is familiar with AMD architectures... doubtful this will be around for very long.
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#47
windwhirl
phanbueyI mean AMD knows about it... MS knows about it...

Reality is MS loves AMD (Xbox is amd based), and is familiar with AMD architectures... doubtful this will be around for very long.
They're expecting to push a fix this month, at least the Windows update side. Not sure if AMD will push a new driver version, too.
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#48
Tomorrow
We dont know if the fix fully restores performance. If it does not then Win11 performance will remain lower than Win10.
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#49
windwhirl
Dev builds already have a fix builtin, so it's probably just a matter of backporting it.

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#50
Broken Processor
The performance hit's are adding up quite nicely but I'm sure they will all get addressed in time. I'll hold off on updating until then.
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