![]() The cause of the problem seems to be that the Threadripper uses all cores but does not push them to the extreme. Without this it would actually be slower than the Haswell. I found out that if I disable SMT and work with only 16(as opposed to 32) logical cores the Threadripper does better. There is something about a "heavy" application that the Threadripper does not seem to handle that well. But for the complex application I am developing the two are roughly equivalent. The two systems execute parallelized code at approximately the same speed.Īctually the Threadripper is much faster than the Haswell when running some simple parallelized F# programs I wrote for testing purposes. I was expecting the performance of parallelized code would be much faster than under my old system with an Intel i7 4770K (Haswell processor), which has only four cores. It is very easy to write parallelized code in F# (as in any functional language) and that is essential for the application I am developing. I use the PC mostly to program in the F# language. The system is running well and is very responsive. Thus, loading up threads 1 and 2 will offer inferior performance to loading up the two distinct physical cores of 1 and 3.I built a PC with an AMD Threadripper 1950X, which has 16 cores. threads 1 and 2) share computational units. For instance, threads 1 and 3 would be physical cores, while cores 2 and 4 would be logical cores attached to physical cores 1 and 3, respectively.Įach logical CPU core pair (e.g. When Hyper-Threading/SMT is enabled, you can consider every other CPU core as physical, and the interlaced ones as logical. It will allow you to compare the relative performance of threads running on specific CPU cores. To aid you in determining the actual performance capabilities of your logical CPU cores, you can use our nifty ThreadRacer tool. Bulldozer) it is the only way to completely disable use of paired cores. The latter lets you restrict use of of non-physical cores to only applications that need real-time performance, without disabling Hyper-Threading entirely, and for some older AMD architectures (e.g. You can either disable Hyper-Threading at the UEFI (BIOS) level, or dynamically, per-process, with Process Lasso’s Hyper-Threaded Core Avoidance. Still, sometimes it is preferred to disable Hyper-Threading to ensure consistent application performance, particularly in real-time applications. You can observe this in the way it interleaves thread utilization across logical CPU cores. However, in the past several years, both Intel and AMD have changed their architectures, and the Windows CPU scheduler is very aware that it needs to prioritize thread scheduling to real CPU cores first. Further complicating matters, the Windows CPU scheduler was not fully aware that it needed to first utilize real CPU cores before loading up Hyper-Threaded logical CPU cores. When Hyper-Threading was first introduced, its logical cores were little more than an add-on, providing as little as 10% of the performance of a real CPU core. For security, given recent MDS ( Microarchitectural Data Sampling) side-channel attacks, MAYBE. Should I Disable Hyper-Threading?įor performance, generally NO. Otherwise, those hardware resources might be sitting idle and unused. This allows for more efficient use of computational resources on the CPU die since two distinct software threads have the opportunity to utilize them at any given time. If neither of the paired cores needs to use the same CPU resources, then they can run simultaneously. It does this by sharing computational units of the physical CPU core between the two virtual CPU cores. Symmetric Multi-Threading (SMT), also known as Hyper-Threading, exposes two logical CPU cores for every physical CPU core.
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