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upstart writes in with an IRC submission for AnonymousCoward:

Ice Lake GPU underperforming? Put it in powersave mode. Wait, what?:

Back in December, Linux users were starting to notice that Ice Lake-equipped laptops were getting better framerates in powersave mode than in performance mode. This Tuesday, Intel developer Francisco Jerez released a patchset to address the conundrum. Jerez begins by noting the fact that if your system bottleneck is I/O, boosting CPU performance won't help—the CPU can't process more data if the I/O subsystem isn't providing it fast enough.

"In IO-bound scenarios (by definition) the throughput of the system doesn't improve with increasing CPU frequency beyond the threshold value at which the IO device becomes the bottleneck."

Jerez goes on to note that pointlessly boosting the CPU into turbo frequencies when there's no additional data for it to process doesn't just hurt power efficiency. In the case of laptop designs, there's typically no room for desktop- or server-style "overengineering"—you've got limited space as well as limited power. This means, among other things, that there's only so much cooling to go around.

"With the current governors [...] the CPU frequency tends to oscillate with the load, often with an amplitude far into the turbo range, leading to severely reduced energy efficiency."

Original Submission