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
Add your own comment

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

#51
eidairaman1
The Exiled Airman
freeagentSigh.. back to 10..
Congrats on mod selection
seth1911With 11 Intel is again the King with Single Chip Design against AMD with MCM :laugh:
Erm its code bias.
Posted on Reply
#52
glsn
question: If I do update to w11, I should also resetup all the apps/configs?
Posted on Reply
#53
nico_80)
just heard about that and, i did the test with latest aida64 is this right?
Posted on Reply
#54
windwhirl
nico_80)just heard about that and, i did the test with latest aida64 is this right?
Those L3 cache numbers are very low, but it's correct if you're running the public release of Windows 11.

Take these ones as an example of where you should be (maybe a little better than mine, but around that range) once Microsoft pushes the fix (hopefully next week):
Posted on Reply
#55
Makaveli
freeagentSigh.. back to 10..
You are a brave soul I never touch a new OS for at least 6 months.
Posted on Reply
#56
zlobby
john_Oh, come on. Just put a "Sponsored by Intel" in Windows 11's boot screen.
Why do you think the Windows logo is blue?
Broken ProcessorThe 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.
I wonder how is the rest of the OS when they botched key things like the scheduler?
Guwapo77Looks like I made the right choice to wait this out. Anyone know when the Windows 11 SP1 disc will ship? :D
Not soon enough. That's for sure.
windwhirlIntel is more affected by VBS than AMD, and you're on the 10th gen, which gets a bigger hit than 11th gen.

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...
Oddly enough Ryzen 2000 are impacted very little. Or at least mine are.
Posted on Reply
#57
windwhirl
zlobbyOddly enough Ryzen 2000 are impacted very little. Or at least mine are.
Have you tested that with core integrity enabled? That's where the big hit is.
Posted on Reply
#58
zlobby
windwhirlHave you tested that with core integrity enabled? That's where the big hit is.
Yep, that's what I'm talking about. Currently on a 2700U PRO. Oddly enough, battery life IS impacted but profiling reveals little to no performance impact.
Posted on Reply
#60
HisDivineOrder
It's almost like changing the scheduler to help Intel out screwed AMD and Microsoft has no actual beta testers, just end users that don't know what they're doing. And all the enthusiasts that might have noticed this were so ticked off by/afraid of the TPM issue, Windows 11 didn't get any real testing.

Almost as if...
Posted on Reply
#61
docnorth
windwhirlIf anything, I detected this months ago and made the corresponding report through Feedback Hub at the time
A few months might not be enough response time for some companies :sleep:
Posted on Reply
#62
windwhirl
docnorthA few months might not be enough response time for some companies :sleep:
So it seems. Though at least they are pushing the fix next week, so there is that.
Posted on Reply
#63
Patriot
TiggerCan we have a Intel/Microsoft conspiracy theory thread instead of crapping it all in here.
I am sorry you don't like your history lesson.
Posted on Reply
#65
owlsplosion
Eh... can't find a new GPU to buy so my games run like shit any way regardless.
Posted on Reply
#66
Mysteoa
zlobbyOddly enough Ryzen 2000 are impacted very little. Or at least mine are.
Mine L3 looks awful.
Posted on Reply
#67
RJARRRPCGP
theGryphonWin 11 sounds like it's as half-baked as Win 8 was... maybe even worse.
Sounds like XP before service packs, where there was a bug that if it crashed once, then on every reboot, I would get the pop-up message about Windows recovering from a serious error, even when Windows XP didn't crash again. I remember the patch for that!
Posted on Reply
#68
Tigger
I'm the only one
PatriotI am sorry you don't like your history lesson.
:laugh:
Posted on Reply
#69
xorbe
This sounds like a Windows problem. Does Linux also lose 15% performance with these same AMD processors? Then it's not the AMD processor "losing" performance ... it's Windows shooting itself in the foot.
Posted on Reply
#70
windwhirl
xorbeThis sounds like a Windows problem. Does Linux also lose 15% performance with these same AMD processors? Then it's not the AMD processor "losing" performance ... it's Windows shooting itself in the foot.
Yes, it's a Windows problem.
Posted on Reply
#71
zlobby
KelutrelExpected resolution in October 2021: www.amd.com/en/support/kb/faq/pa-400
I wonder what kind of new attack surfaces these 'fixes' will introduce? I bet on 4 months before Win 11 blows badly with some nasty hack.
Posted on Reply
#72
tabascosauz
Haven't actually noticed any appreciable difference in CPU performance in the benches and games, but the scheduler issue is very obvious. Windows 10 got pretty good at exclusively keeping foreground apps (benches, productivity and games) on the 2 preferred cores.

Core 7 is supposed to be assigned background tasks only. Windows 11 is literally running an entire game exclusively on Core 7 as we speak:



I don't like conspiracy theories usually, but this is such a ridiculous regression from the Windows scheduler and CPPC2 having worked just fine together for months.
Posted on Reply
#73
maxfly
Wake me next year when the fully patched and truly usable 11 gets released please.
Posted on Reply
#74
Bomby569
good luck for all the beta testers out there
Posted on Reply
#75
windwhirl
Bomby569good luck for all the beta testers out there
Eh, it's already fixed in Dev, so MS will probably just backport it to RTM
Posted on Reply
Add your own comment