SoylentNews

takyon writes:

Amazon Announces Graviton2 SoC Along With New AWS Instances: 64-Core Arm With Large Performance Uplifts

The new Graviton2 SoC is a custom design by Amazon's own in-house silicon design teams and is a successor to the first-generation Graviton chip. The new chip quadruples the core count from 16 cores to 64 cores and employs Arm's newest Neoverse N1 cores. Amazon is using the highest performance configuration available, with 1MB L2 caches per core, with all 64 cores connected by a mesh fabric supporting 2TB/s aggregate bandwidth as well as integrating 32MB of L3 cache.

Amazon claims the new Graviton2 chip is[sic] can deliver up to 7x higher performance than the first generation based A1 instances in total across all cores, up to 2x the performance per core, and delivers memory access speed of up to 5x compared to its predecessor. The chip comes in at a massive 30B transistors on a 7nm manufacturing node - if Amazon is using similar high density libraries to mobile chips (they have no reason to use HPC libraries), then I estimate the chip to fall around 300-350mm² if I was forced to put out a figure.

The memory subsystem of the new chip is supported by 8 DDR4-3200 channels with support for hardware AES256 memory encryption. Peripherals of the system are supported by 64 PCIe4 lanes.

Original Submission

takyon writes:

Arm's New Cortex-A78 and Cortex-X1 Microarchitectures: An Efficiency and Performance Divergence

Today for Arm's 2020 TechDay announcements, the company is not just releasing a single new CPU microarchitecture, but two. The long-expected Cortex-A78 is indeed finally making an appearance, but Arm is also introducing its new Cortex-X1 CPU as the company's new flagship performance design. The move is not only surprising, but marks an extremely important divergence in Arm's business model and design methodology, finally addressing some of the company's years-long product line compromises.

[...] The new Cortex-A78 pretty much continues Arm's traditional design philosophy, that being that it's built with a stringent focus on a balance between performance, power, and area (PPA). PPA is the name of the game for the wider industry, and here Arm is pretty much the leading player on the scene, having been able to provide extremely competitive performance at with low power consumption and small die areas. These design targets are the bread & butter of Arm as the company has an incredible range of customers who aim for very different product use-cases – some favoring performance while some other have cost as their top priority.

All in all (we'll get into the details later), the Cortex-A78 promises a 20% improvement in sustained performance under an identical power envelope. This figure is meant to be a product performance projection, combining the microarchitecture's improvements as well as the upcoming 5nm node advancements. The IP should represent a pretty straightforward successor to the already big jump that were the A76 and A77.

[...] The Cortex-X1 was designed within the frame of a new program at Arm, which the company calls the "Cortex-X Custom Program". The program is an evolution of what the company had previously already done with the "Built on Arm Cortex Technology" program released a few years ago. As a reminder, that license allowed customers to collaborate early in the design phase of a new microarchitecture, and request customizations to the configurations, such as a larger re-order buffer (ROB), differently tuned prefetchers, or interface customizations for better integrations into the SoC designs. Qualcomm was the predominant benefactor of this license, fully taking advantage of the core re-branding options.

[...] At the end of the day, what we're getting are two different microarchitectures – both designed by the same team, and both sharing the same fundamental design blocks – but with the A78 focusing on maximizing the PPA metric and having a big focus on efficiency, while the new Cortex-X1 is able to maximize performance, even if that means compromising on higher power usage or a larger die area.

While Cortex-A78 will only improve performance by around 7% from microarchitectural changes alone, Cortex-X1 will improve performance by up to 30% due to a wider design, doubling of most cache sizes, and other changes. Cortex-X1 cores are also expected to reach 3 GHz on a "5nm" node, delivering even more performance. The Cortex-X1 cores could use up to 50-100% more power than Cortex-A77/A78. Cores could be arranged in a 1+3+4 or 2+2+4 setup of Cortex-X1, Cortex-A78, and Cortex-A55 cores.

See also: Arm Announces The Mali-G78: Evolution to 24 Cores

Original Submission