Jon Kennedy

Nvidia dev tech engineer. Opinions are my own, blah, blah, blah... 😁

[NVIDIA Game Dev @NVIDIAGameDev]

Tomorrow at 9 AM PT, get your questions answered about NVIDIA #RTX Path Tracing.

Join our #AMA to discover how you can take advantage of NVIDIA technologies to accurately recreate the physics of all light sources in a scene.

Start asking questions now.

[Jon Kennedy @jon_c_kennedy]

Definitely worth attending if you are interested in real-time pathtracing!

[NVIDIA AI Developer @NVIDIAAIDev]

Join this Ask Me Anything on June 6th to see how you can integrate NVIDIA RTX™ Path Tracing in your games while maximizing your performance with DLSS.

Begin asking your questions today: https://t.co/zQsAkZaaDh

[Simon McIntosh-Smith @simonmcs]

Isambard 3 announced at @ISChpc today! 384 NVIDIA Grace Superchips, 55296 @Arm cores, delivered by @HPE_Cray. Will be one of the most powerful and energy efficient systems in the UK. Hear more at the Arm BoF and AHUG workshop in Hamburg @GW4Alliance https://t.co/oQhPQn8Gof

[Jon Kennedy @jon_c_kennedy]

@CapFrameX @Dachsjaeger @D_S_O_Gaming Am I reading this right that disabling e-cores has 3% more frames within 2ms of each other?

[Jon Kennedy @jon_c_kennedy]

@Dachsjaeger @D_S_O_Gaming I would think there *is* a difference in fluidity between configs. SMT/e-cores increase variance, depending on where different threads are run.
If a thread is limiting perf and it suddenly runs on an e-core, or has to share resources on an SMT core, then it will cause variance.

[Jon Kennedy @jon_c_kennedy]

@matiasgoldberg IIRC it can speculatively get the neighbouring cachelines. Not a good thing if you are already hitting false sharing!

[Jon Kennedy @jon_c_kennedy]

@matiasgoldberg don't forget the prefetcher which can catch you out with false sharing - might want padding[256] to be sure... 🫤

[Jon Kennedy @jon_c_kennedy]

@CapFrameX @antdavis1986 @Dachsjaeger @matiasgoldberg but isn't that due, in part, to the massive benefit of the huge L3 in the 5800X3D? Combine that cache with a fast CPU and its a killer combo!
The faster CPUs get, the more other resources become the bottleneck, like L3 and DRAM.

[Jon Kennedy @jon_c_kennedy]

@matiasgoldberg @Dachsjaeger HT doesn't always deliver - always worth trying to disable it to see if you get extra perf 🤔
Unless the SW threads are pinned, I wouldn't expect a core to be 100% utilised in a game.

[Jon Kennedy @jon_c_kennedy]

@toncijukic @matiasgoldberg @Dachsjaeger I've also seen issues a unity title with negative scaling related to core count. Too many threads trying to get work in a badly designed job system that only has a single job queue lock - results in job queue starvation.

[Jon Kennedy @jon_c_kennedy]

@hoytehablode @Dachsjaeger @matiasgoldberg I'd be interested in seeing if there is a perf gain by disabling the E cores

[Jon Kennedy @jon_c_kennedy]

@CapFrameX @Dachsjaeger @matiasgoldberg I think single thread perf is still pretty important, but cinebench MT is not representative at all of games, despite certain IHV's insistance that it is 😉
DRAM and L3 cache can have massive impacts. Ultimately though, it is all game dependent!

[Jon Kennedy @jon_c_kennedy]

@Dachsjaeger @matiasgoldberg HT off won't help as its not using the HT cores by the looks of it (core 1, 3, 5 etc are 0%. If you can capture an ETW/ETL file, that should tell us something.
You can view by thread, then by CPU to see if it is bouncing around but fully saturating 'a' single core.

[Jon Kennedy @jon_c_kennedy]

@Dachsjaeger @matiasgoldberg Yes - could still be CPU bound though. Either for 70% of the workload (waiting on the GPU for the rest), or the bound thread could just hop CPUs, so it is 70% on core 15 and 30% on core N == 100%

[Jon Kennedy @jon_c_kennedy]

@matiasgoldberg @Dachsjaeger Note that CPU utilisation shown will be for the full CPU, so could easily be CPU bound on a single thread. What CPU is he using and what freq is it clocked at? Just open up task manager to see whats going on (per logical core)...

[Jon Kennedy @jon_c_kennedy]

@TheAnimator @KostasAAA Looks awesome! Let me know if I can help you with the UK stuff :D

[Laura Reznikov 🇺🇦 @TheAnimator]

https://t.co/4fADnbS3Ie is open for business! 😱 Ever wanted graphics geek swag that wasn’t conference or business branded? Me too! It’s currently setup USA only as I figure out shipping etc, but if you send me a message I’ll see what I can do. #rendering #SmallBusiness

[Digital Foundry @digitalfoundry]

In the space of just four years we've somehow moved from a path-traced Quake 2 to a path-traced Cyberpunk 2077... but how? Here's @Dachsjaeger with a new Tech Focus on the hardware and software advances that made this remarkable achievement possible: https://t.co/PxHhK1ede5

[Jon Kennedy @jon_c_kennedy]

Whoot - Launching on the 11th - looking forward to seeing this out there for everyone to see 😁:
https://t.co/vwYLmHmnjI

[Intel @intel]

Today, we lost a visionary.

Gordon Moore, thank you for everything.