1
Applications / Re: ArcaOS 5.1 - First Impressions
« on: January 02, 2024, 08:32:09 pm »I believe Hyperthreading is an Intel only feature - meaning it only appears on Intel CPUs. If I understand it correctly Hyperthreading was/is a technology by Intel to provide some of the benefit of multiple cores without actually having all of the hardware of the multiple cores.
It is not an Intel only feature, it appeared originally on minicomputers specialised in database jobs and on some workstation/server chips, a number of the later SPARC chips have hyperthreading. The original idea is literally to speed up database jobs by having a parallel hardware threads packing inherently inefficient relational database code into something more efficiently executed on a normal CPU core, this gave you a 7 to 20% speedups in specialised tasks for for a 3% to 8% increase in transistor count. Intel originally introduced Hyperthreading on Xeons as an answer to Sun SPARC's with hyperthreading close to 20 years ago.
Even though current versions of HT are a bit more generic than the original designs they still have the same flaw, the code is packed out of order, and there is a slight unpredictable (fuzzy) delay in reordering it, not an issue in most cases, but for hard real time work such as some drivers and audio applications that get their timing reference from the soundcard rather than the CPU, this leads to hiccups. As an example on Windows, most professional audio programs that require a single timing reference (not all do) simply turn off HT via ACPI while they are running, turning it back on again when they exit.
SPARC server chips were not doing any hard real time work so this was never really an issue with them, however it became an issue as soon as Xeons came out since they were being used for real time audio and video work. I still turn HT off on my Intel machines regardless of OS due to past experiences with driver and app issues, and even on Windows I have never really found an application that takes advantage of HT to such a degree to make me consider turning it on again, but your milage may vary.