Moving past speculation: How deterministic CPUs deliver predictable AI performance

For more than three decades, modern CPUs have relied on speculative execution to keep pipelines full. When it emerged in the 1990s, speculation was hailed as a breakthrough — just as pipelining and superscalar execution had been in earlier decades. Each marked a generational leap in microarchitecture. By predicting the outcomes of branches and memory loads, processors could avoid stalls and keep execution units busy. But this architectural shift came at a cost: Wasted energy when predictions failed, increased complexity and vulnerabilities such as Spectre and Meltdown. These challenges set the stage for an alternative: A deterministic, time-based execution model. As David Patterson observed in 1980, “A RISC potentially gains in speed merely from a simpler design.” Patterson’s prin [...]