P870 Raises RISC-V Performance Bar

SiFive’s P870 CPU is a high-throughput RISC-V core, implementing a wide microarchitecture and promising performance exceeding that of Arm’s fastest Cortex-A CPU.

Joseph Byrne

Already licensing the highest-performance RISC-V CPU, SiFive now offers an even speedier application-processing core. By adding execution resources and reordering capability, the P870 raises per-cycle throughput a claimed 40% above that of the P670 introduced last year. It also tops that of the Arm Cortex-A720, the first time a licensable RISC-V core has outpaced a contemporaneous workhorse Cortex-A CPU.

SiFive positions the P870 for chips addressing network, storage, high-end consumer, and automotive use. For the lattermost market, the company offers the P870-A that adds safety features. These are closed designs—like the controller functions targeted by simpler RISC-V CPUs—that don’t require a variety of turnkey software for an end user to install. Such software isn’t yet available for RISC-V.

SiFive expects the P870-A RTL to be available in 2025, and the base P870 will be available by mid-2024, with the first customer chips likely to sample a year later. In the meantime, the company faces a credibility problem. Each of the past few years it has introduced a new application CPU but can’t yet point to major customers ramping production. Reports have surfaced that the company is ceasing standard-product development to focus on custom cores and terminating much of its management and staff, raising the question of whether the company will complete P870 development. SiFive, however, states that there are no changes to its roadmap or business model.