Intel Skylake CPUs have ‘inverse Hyper Threading’ to boost single-thread performance

The German website Heise reports that Skylake CPUs might have a special feature to boost single-thread performance, the site calls it reverse Hyper Threading. The feature pretty much combines several physical cores into a single ‘Super Core’. In other words, the feature combines features and performance of multiple physical cores into a single virtual core.


(Credits: Heise / C’T Labs.  Translation: Kerne = Cores / Puntke = Points)

Heise found unusual behavior of the Core i7 6700K Skylake CPU when performing tests with the SPEC CPU2006 Suite. The single-thread performance of the CPU was found to be 2.4x faster than the Haswell architecture based Core i7 4790K CPU. When multiple cores and threads were tested, the difference in performance between the Skylake and Haswell CPU was a lot less. The site reports a difference of about 20% when multiple threads are used instead of about 170% between single-thread performance.

Heise speculates that Intel might have added a feature to the CPU that allows a second core to assist the first core with e.g. functional units, caches or buffers. Heise speaks about a single virtual core that is made up of several physical cores. This isn’t actually something new, a similar technology was announced by the company Soft Machines at the end of 2014. This company, founded by two former Intel employees has developed a technology they call VISC.

On its website Soft Machines writes, “The VISC architecture, based on the concept of “virtual cores” and “virtual hardware threads”, enables dynamic allocation and sharing of resources across cores.”

The company also promises to increase performance 2 to 4 times, which is on par with the performance increase reported by Heise. So far it’s only speculation of the website, actual details on the processor are expected at the Intel Developer Forum that’s held the 18th of August this year.