First Windows 11 Patch Tuesday Makes Ryzen L3 Cache Latency Worse, AMD Puts Out Fix Dates

[btarunr]

Microsoft on October 12 put out the first Cumulative Updates for the new Windows 11 operating system, since its October 5 release. The company's monthly update packages for Windows are unofficially dubbed "patch Tuesday" updates, as they're scheduled to come out on the second Tuesday of each month. Shortly after Windows 11 launch, AMD and Microsoft jointly discovered that Windows 11 is poorly optimized for AMD Ryzen processors, which see significantly increased L3 cache latency, and the UEFI-CPPC2 (preferred cores mechanism) rendered not working. In our own testing, a Ryzen 7 2700X "Pinnacle Ridge" processor, which typically posts an L3 cache latency of 10 ns, was tested to show a latency of 17 ns. This was made much worse with the October 12 "patch Tuesday" update, driving up the latency to 31.9 ns.

AMD put out a statement on social media, which surfaced on Reddit. The company stated that patches for the two issues have been developed, and specified dates on which they'll be released. The patch for the Preferred Cores (UEFI-CPPC2) bug will be released on October 21. Customers can request the patch even earlier. By "customers," AMD is probably referring to big enterprise customers running mission-critical applications on Threadripper or EPYC-powered workstations. The L3 cache latency bug will be fixed through the Windows Update channel, its release is scheduled for October 19.



If rumors surrounding the late-October/early-November launch dates of 12th Gen Intel Core "Alder Lake" processors are true, then the situation with these patches will have a direct impact on AMD. Processor reviewers will be compelled to use Windows 11 for their Core "Alder Lake" testing, as the new operating system supposedly has greater awareness of the heterogeneous core design. The switch to Windows 11 will force a re-bench of all processors, including the AMD Ryzen chips. With AMD cautioning of an up to 15% performance hit from the added cache latency and Preferred Cores bugs, results of AMD processors in 12th Gen Core launch reviews could be affected. It is advisable for AMD to reach out to the press with these patches immediately, if they are ready.

View at TechPowerUp Main Site

 

[Metroid]

Finally, a light in the end of the tunnel, on windows 10 my 5900x used to get up to 4.9ghz 2 threads, right now on windows 11 maximum at 4.6ghz 2 threads, default, no overclocking. After I found that out, I decided to overclock all cores to 4.6ghz and has been stable so far, will revert to default settings once they implement a fix, want that 4.9ghz again on 2 threads using windows 11.

 

[Fouquin]

If only tons of insider testers had reported this months ago during the test builds and hadn't been completely ignored. If only Microsoft still did proper QC...

 

[Ruru]

Hah, I got already bad results with my 3600

 

[Crackong]

Windows update break things again and even worse.....surprised ?

 

[Ruru]

Windows update break things again and even worse.....surprised ?

Yeah nothing new here..

 

[R-T-B]

There was no excuse to not release the patch for the l3 issue THIS tuesday. This is a major fail and looks very suspect indeed.

 

[Ruru]

There was no excuse to not release the patch for the l3 issue THIS tuesday. This is a major fail and looks very suspect indeed.

Could this be a reason why AMD has performance hit with Win11?

 

[R-T-B]

Could this be a reason why AMD has performance hit with Win11?

I don't like indulging in conspiracy theories normally, but this is indeed starting to smell like something very iffy.

 

[Ruru]

I don't like indulging in conspiracy theories normally, but this is indeed starting to smell like something very iffy.

Yeah I got also shitty results when I ran AIDA memory benchmarks. Too bad that I didn't run those before I upgraded from Win10 dammit.

edit: The CPU is AMD 3600 @ PBO +200

 

[Aretak]

If only tons of insider testers had reported this months ago during the test builds and hadn't been completely ignored. If only Microsoft still did proper QC...

They do. Or rather... you do. Windows for consumers is a constant rolling beta designed so that Microsoft can identify and fix issues for enterprise customers. Why pay a team to hunt for bugs when you can have millions of people do it for free? It's nothing new. Windows 10 was the exact same way, with completely broken updates regularly pushed to consumers throughout its lifetime so that any bugs in them could be patched later. It seemed like every single Patch Tuesday brought along some new major issue(s) that broke people's machines in various fun and exciting ways, though in reality I'm sure one or two passed without incident.

 

[R-T-B]

Yeah I got also shitty results when I ran AIDA memory benchmarks. Too bad that I didn't run those before I upgraded from Win10 dammit.

edit: The CPU is AMD 3600 @ PBO +200

The even iffier part is it's been fixed in dev branch for months...

They seem aware but unwilling to push the fix on time for some weird reason.

 

[Metroid]

lol, I bet a not yet released product, example, Intel alder lake must be running very smooth, a 12 months released cpu like amd ryzen 5900x has problems ehhe, I wonder where is the faulty here, amd or microsoft.

 

[R-T-B]

lol, I bet a not yet released product, example, Intel alder lake must be running very smooth, a 12 months released cpu like amd ryzen 5900x has problems ehhe, I wonder where is the faulty here, amd or microsoft.

There is simply no way AMD could be at fault as far as I can see. This is full-on external ms sabotage with suspicious motivations.

 

[Mussels]

I'm always anti-conspiracy, but this ones really weird
patches that make it worse when the fix is already on the dev channel?
Right before windows 11 is required to review alder lake CPUs?


If it's not malicious, its massive incompetence.

 

[R-T-B]

I'm always anti-conspiracy, but this ones really weird
patches that make it worse when the fix is already on the dev channel?
Right before windows 11 is required to review alder lake CPUs?


If it's not malicious, its massive incompetence.

Yeah, with you there. Either conclusion at this point is bad.

 

[Chomiq]

"We fixed it! ... We fixed it, right? ..."

I'm sure their BETA testers have tested it before release, oh wait...

 

[maxfly]

Yeah this smells real bad. I was expecting to read something about a fix being implemented...this is ridiculous.

 

[TheUn4seen]

Got to love that Microsoft incompetence. "She'll be right, push that into production, we'll figure out problems later". In every company I ever worked in anyone working like that would be fired rather quickly, and yet, is seems it is just a normal day in most corporations. It seems that ignorance and incompetence is proportional to the company size.

 

[Turmania]

A patch to fix it but it actually makes it worse... you couldn`t make this up but this is AMD and Microsoft...

 

[R-T-B]

A patch to fix it but it actually makes it worse... you couldn`t make this up but this is AMD and Microsoft...

To be fair, this patch never claimed it was for the L3 issue.

At least they are honest about their lack of priorities.

 

[Jism]

If only tons of insider testers had reported this months ago during the test builds and hadn't been completely ignored. If only Microsoft still did proper QC...

You know that if your using windows these days your the beta tester right?

 

[Sybaris_Caesar]

I had similar suspicions. But didn't wanna get lambasted by puritanical anti-conspiracy white knights so stayed shut. If forum seniors notice the same thing I might add that Microsoft isn't ready everytime AMD does something new. Or in this case breaks things on AMD when they themselves do something new. While Intel compatibility was addressed even before their big.LITTLE processors hit the market.

 

[R-T-B]

You know that if your using windows these days your the beta tester right?

I think you found his complaint.

I had similar suspicions. But didn't wanna get lambasted by puritanical anti-conspiracy white knights so stayed shut. If forum seniors notice the same thing I might add that Microsoft isn't ready everytime AMD does something new. Or in this case breaks things on AMD when they themselves do something new. While Intel compatibility was addressed even before their big.LITTLE processors hit the market.

To be completely honest, that isn't really a conspiracy in and of itself. Intel is the market leader, so of course they get priority. That's capitalism, not conspiracy.

What IS suspect is how a perfectly fine scheduler just suddenly "broke" right before alder lake came out. How the "patch" fixing this on dev branch is taking far, far too long to make it to stable. It's beyond explanation at this point.

 

[Luminescent]

No big deal, we will update to windows 11 after a few years or when some important applications won't start if you don't have latest windows.