Dual cpu speed problems

[Evolist_ua]

Hello, I found out about one feature of Windows, maybe this is the problem?

"Windows supports more than 64 logical cores, and they are divided into groups to perform tasks more efficiently. A logical core can be either a separate processor in a socket, or a physical CPU core or SMT thread.

During boot, the operating system creates groups of logical processors, but their number cannot exceed 64 in one group. If there are more cores, then two groups are created. In the case of 32 cores/64 threads or a CPU with fewer cores, there are no problems - there is one group. But in the case of 65++ threads there are two groups.

On systems with 64 or fewer logical cores, applications run smoothly because Windows associates them with the same group. If there are two groups, then the tasks are alternately assigned to the first or second group. And an application can only access its group's threads - unless it recognizes multiple groups. Thus, the application must be able to work with several groups of logical cores. If there is no such support in the application, then the number of logical cores is limited to 64, and processor resources are not fully used."

[Nejc Kilar]

Howdy folks! You are not forgotten :) Or shall I say we are not forgotten because I also have 64 core Threadripper which has some of the issues you mentioned.

The issue is a bit hard for us to diagnose right now but we are putting effort into resolving it. We tried a couple of solutions internally with not very good results but then some solutions are already being rolled out as they do improve performance. These latest improvements mainly affect high thread count CPUs not necessarily 2S systems.

So please if you have issues similar to the ones outlined in this thread please let us know. Any new info about different system configurations struggling with these kinds of issues will make it easier for us to have a more complete improvement.

[Evolist_ua]

I saw in the latest daily build “Improved performance of Corona renderer with bucket rendering on high-core count machines”, I tested it, nothing has changed compared to the release version of the 11th corona. Still bad speed without corona bitmap, the difference in the number of rays is enormous

[TomG]

The fix is for high core count single CPU machines - we're still investigating potential issues on high core count multi-CPU systems. Thanks!

[Evolist_ua]

The fix is for high core count single CPU machines - we're still investigating potential issues on high core count multi-CPU systems. Thanks!

In this case, this is a single-processor system, I specifically attached the task manager, where you can see that it is 3990x (64 cores/128 threads). There is no way to test it on a dual-processor system right now.

[TomG]

Interesting, as this is the "Dual cpu speed problems" thread ;)

[Evolist_ua]

Interesting, as this is the "Dual cpu speed problems" thread ;)

Yes))

I have a system with a dual processor, but I thought that switching to a high-performance single-processor system would help me, but as it turned out, I have the same problem))

P.S. on my system with 5950x (16 cores/32 threads) everything is fine.

[TomG]

The report is welcomed of course! I was looking to see if we had a better thread to report it under, but for now there isn't one, we might set one up though if we hear more issues with single CPUs. On the 3990X we have for testing, this fix did indeed make a difference, so this is interesting.