Ryzen And Windows 10: Does AMD Have A Performance Problem?

Image: AMD

A new architecture from a processor vendor is always going to snag the attention of hardware lovers and their magnifying glasses. AMD's Zen, found in its freshly stamped Ryzen line is the current target and amongst all the numbers, testers have discovered something interesting; a discrepancy in the Ryzen's performance and Windows 10. But which party is to blame — if any?

AMD always falls under more scrutiny than Intel, which is unfortunate, but expected. When you've played second fiddle for so long, there's a massive expectation for each new product to be "the one", the silicon jewel that restores the company to its former glory.

Yes, the Athlon days are well and truly behind us, but AMD is packed with smart cookies; there's every chance one day it'll knock one out of the park.

That's not to say Intel is by any means perfect. It's the king of the CPU hill, but that unchallenged position appears to have translated into relaxing its QA processes. Bugs with the company's chips have started to pop up with increasing frequency and although they've had little bearing on consumers, they are worrying nonetheless.

Today, however, it's AMD under the spotlight. Allyn Malventano over a PCper, after hearing about some odd numbers from Ryzen, decided to do some digging. Here's an explanation of the issue:

Initial reviews of AMD's Ryzen CPU revealed a few inefficiencies in some situations particularly in gaming workloads running at the more common resolutions like 1080p, where the CPU comprises more of a bottleneck when coupled with modern GPUs. Lots of folks have theorized about what could possibly be causing these issues, and most recent attention appears to have been directed at the Windows 10 scheduler and its supposed inability to properly place threads on the Ryzen cores for the most efficient processing.

PCper even went so far as to cook up a custom app to see just how Windows was managing its threading workloads. Malventano's investigation is peppered with more graphs than a marketing PowerPoint by Microsoft's Excel team, but taken together tell an interesting story:

Information from this custom application, along with the storage performance tool example above, clearly show that Windows 10 is attempting to balance work on Ryzen between cores in the same manner that we have experienced with Intel and its HyperThreaded processors for many years ... it validates that Windows 10 is correctly enumerating the core structure of Ryzen and thus the scheduling comparisons we made above are 100% accurate. Windows 10 does not have a scheduling conflict on Ryzen processors.

The conclusion suggests that there is a problem, one AMD itself is looking into, but it doesn't involve Windows 10. Well, the scheduler anyway. Maybe not the definitive answer some might be looking for, but it does mean testers can start looking into other areas.

AMD Ryzen and the Windows 10 Scheduler — No Silver Bullet [PCper]


Comments

    This video provides an interesting insight about what causes the problem, and says using a NUMA scheduler (similar to how windows manages dual socket xeon boards) will prevent threads spilling over between each Ryzen CCX unit, and hopefully reduce the issues we are seeing. https://www.youtube.com/watch?v=40h4skxDkh4

    Are you sure? Seems like they're pretty certain it's a scheduler issue.

    http://windowsreport.com/amd-ryzen-performance/

      The article is badly worded, "Microsoft has officially acknowledged this issue and confirmed is working on a fix." To be more clear, what Microsoft did was acknowledge the issue existed and would look into it, no confirmation of working on anything or even that any Windows component was responsible.

      That's not to say there isn't a software change Microsoft can do, just that nothing has been confirmed yet.

      Last edited 12/03/17 5:42 pm

    Ryzen's problem isn't physical vs logical core handling, its bigger problem is windows scheduler is unaware that it should be treating each core complex as non-uniform memory, and thus should be allocating tasks using similar cache calls to a single core complex. What happens at the moment is that doesn't occur, causing cache misses. The addition of SMT just adds a higher chance of causing a cache miss.

      Amd doesn't have a problem. Its within windows 10. Since this can be fixed with an update, I see no real reason to make a big deal out of it. Its the tinyest difference in the world to be concerned about the performance. It will be fixed.

    Here is the quick version - its a new CPU and needs lots of optimisations by both software and hardware which will all come now that the CPU is in the hands of both Microsoft, game devs and hardware manufacturers.

    There hasn't been a new CPU from AMD in so long with this much performance, much like the Switch, its all being blown out of proportion because everyone's watching with baited breath.

    The Ryzen CPUs are monsters. Intel still appears to have the upper hand for single threaded performance, but under multi threaded performance these CPUs shine.

    Like any tech - if your an early adopter expect these issues and let's give it time to be resolved. For those of us who aren't, we can calmly wait for the appropriate software and hardware patches to roll out. This is the line that experienced reviewers are telling people!

    I'll definitely be upgrading to a Ryzen CPU for both work and play.

    The AM4 platform has issues which will be ironed out over the next few months, that much is certain. However the higher clocked Intel cpu's (some go up to 5ghz) will still be better performing in the games that are poorly optimized for multicore processors.

    Intel may try and beat AMD out by simply moving to 5ghz parts, which will likely leave AMD's 4gzh processors in the dust, and given how new 14nm is, its unlikely AMD will raise stock clocks until next year (Zen2).

      considering Ryzen are not gaming chips, i actually really surprised how well they are holding up in gaming tests compared to Intel's chips. the next 6 months will be most interesting for sure. exciting times ahead.

    I swear we've had this issue back in the bulldozer days. Benchmarks came in and they were crap, and AMD said it's an OS issue, wait for Windows 8.

      Difference this time is that we can make changes ourselves and see the difference very clearly... and it's sometimes as high as 25%, whereas Bulldozer only had 5% or so to gain.

    Will be discussing this in a video, during testing we saw they were using windows 10, AMD even state that they did their primary testing on windows 10. This being the case they didn't forsee this bugs? I could be wrong but if you are doing testing on a new chip and using windows 10, you can't exactly blame the OS.

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