PCI-SIG DevCon 2024 – 32^nd Anniversary

For more than a decade, Cadence has been well-known in the industry for its strong commitment and support for PCIe technology. We recognize the importance of ensuring a robust PCIe ecosystem and appreciate the leadership PCI-SIG provides. To honor the 32^nd anniversary of the PCI-SIG Developer’s Conference, Cadence is announcing a complete PCIe 7.0 IP solution for HPC/AI markets.

Why Are Standards Like PCIe So Important?

From the simplest building blocks like GPIOs to the most advanced high-speed interfaces, IP subsystems are the lifeblood of the chipmaking ecosystem. A key enabler for IP has been the collaboration between industry and academia in the creation of standards and protocols for interfaces. PCI-SIG drives some of the key definitions and compliance specifications and ensures the interoperability of interface IP.

HPC/AI markets continue to demand high throughput, low latency, and power efficiency. This is fueling technology advancements, ensuring the sustainability of PCIe technology for generations to come. As a close PCI-SIG member, we gain valuable early insights into the evolving specs and the latest compliance standards. PCIe 7.0 specifications and beyond will enable the market to scale, and we look forward to helping our customers build best-in-class cutting-edge SoCs using Cadence IP solutions.

Figure 1. Evolution of PCIe Data Rates (source PCI-SIG)

What’s New This Year at DevCon?

At DevCon ’24, the PCIe 7.0 standard will take center stage, and Cadence is showing off a full suite of IP subsystem solutions for PCIe 7.0 this year.

What Sets Cadence Apart?

At Cadence, we believe in building a full subsystem for our testchips with eight lanes of PHY along with a full 8-lane controller. Adding a controller to our testchip significantly increases the efficiency and granularity in characterization and stress testing and enables us to demonstrate interoperability with real-world systems. We are also able to test the entire protocol stack as an 8-lane solution that encompasses many of the applications our customers use in practice. This approach significantly reduces the risks in our customers’ SoC designs.

Figure 2: Piper - Cadence PHY IP for PCIe 7.0

Figure 3: Industry’s first IP subsystem for PCIe 7.0

Which Market Is This For?

At a time when accelerated computing has gone mainstream, PCIe links are going to take on a role of higher importance in systems. Direct GPU-to-GPU communication is crucial for scaling out complex computational tasks across multiple graphics processing units (GPUs) or accelerators within servers or computing pods. There is a growing recognition within the industry of a need for scalable, open architecture in high-performance computing. As AI and data-intensive applications evolve, the demand for such technologies will likely increase, positioning PCIe 7.0 as a critical component in the next generation of interface IP.

Here's a recent article describing a potential use case for PCIe 7.0.

Figure 4: Example use case for PCIe 7.0

Why Are Optical Links Important?

It takes multiple buildings of data centers to train AI/ML models today. These buildings are increasingly being distributed across geographies, requiring optical fiber networks that are great at handling the increased bandwidth over long distances. However, these optical modules soon hit a power wall where all the budgeted power is used to drive the signal from point A to point B, and there is not enough power left to run the actual CPUs and GPUs. Such scenarios create a need for non-retimed, linear topologies. Linear Pluggable Optics (LPO) links can significantly reduce module power consumption and latency when compared to traditional Digital Signal Processing (DSP) based retimed optical solutions, which is critical for accelerating AI performance. Swapping from DSP-based solutions to LPO results in significant cost savings that help drive down expenditure due to lower power and cooling requirements, but this requires a robust high-performance ASIC to drive the optics rather than retimers/DSP.

To showcase the robustness of Cadence IP, we have demonstrated that our subsystem testchip board for PCIe 7.0 can successfully transmit and receive 128GT/s signals through a non-retimed opto-electrical link configured in an external loopback mode with multiple orders of margin to spare.

Figure 5: Example of ASIC driving linear optics

Compliance Is Key

For PCIe 6.0, the official compliance program has not started yet; this is typical for the SIG where the official compliance follows a few years after the spec is ratified to give enough time for the ecosystem to have initial products ready, and for test and equipment vendors to get their hardware/software up and running. At this time, PCIe Gen6 implementations can only be officially certified up to PCIe 5.0 level (the highest official compliance test suite that the SIG supports). We have taken our PCIe 6.0 IP subsystem solution to the SIG for multiple process nodes, and they are all listed as compliant. You can run this query on the pcisig.com website under the Developers->Integrators list by making the following selections:

Due to space limitations, not all combinations could be tested at the May workshop (e.g., N3 root port) – this will be tested in the next workshop.

Also, the SIG just held an “FYI” compliance event this week to bring together the ecosystem for confidential testing (no results were reported, and data cannot be shared outside without violating the PCI-SIG NDA). We participated in the event with multiple systems and can report that our systems have done quite well. The test ecosystem is not mature yet, and a few more FYI workshops will be conducted before the official compliance for 6.0 is launched. We have collaborated with all the key test vendors for electrical and protocol testing throughout the year. As early as the middle of last year, we were able to provide test cards to all these vendors to demo PCIe 6.0 capabilities in their booths at various events. Many of them recorded these videos, and they can be found online.

• Cadence Subsystem IP for PCIe 6.0: Protocol and Electrical Testing
• Cadence Subsystem IP for CXL Protocol Test Demo
• Cadence Subsystem IP for CXL2.0/3.0 Protocol Test Demo
• Cadence Subsystem IP for PCIe 6.0: Protocol Stack Demo

More at the PCI-SIG Developers Conference

Check us out at the PCI-SIG Developer’s conference on June 12 and 13 to see the following demonstrations:

• Robust performance of Cadence IP for PCIe 7.0 transmitting and receiving 128GT/s signals over non-retimed optics
• Capabilities of Cadence IP for PCIe 7.0 measured using oscilloscope instrumentation detailing its stable electrical performance and margin
• The reliability of Cadence IP for PCIe 6.0 interface using Test Equipment to characterize the PHY receiver quality
• A PCI-SIG-compliant Cadence IP subsystem for PCIe 6.0 optimized for both power and performance

As a leader in PCI Express, Anish Mathew of Cadence will share his valuable insights on an important topic: “Impact of UIO ECN on PCIe Controller Design and Performance,” highlighting the strides made by the Cadence design team in achieving this implementation.

Figure 6: Cadence UIO Implementation Summary

Summary

Cadence showcased PCIe 7.0-ready IP at PCI-SIG Developers Conference 2023 and continues to lead in PCIe IP development, offering complete solutions in advanced nodes for PCIe 7.0 that will be generally available early next year. With a full suite of solutions encompassing PHYs, Controllers, Software, and Verification IP, Cadence is proud to be a member of the PCI-SIG community and is heavily invested in PCIe. Cadence was the first IP provider to bring complete subsystem solutions for PCIe 3.0, 4.0, 5.0, and 6.0 with industry-leading PPA and we are proud to continue this trend with our latest IP subsystem solution for PCIe 7.0, which sets new benchmarks for power, performance, area, and time to market.

PCI-SIG DevCon 2024 was a great success for Cadence. We posted the blog, Cadence Demonstrates Complete PCIe 7.0 Solution at PCI-SIG DevCon ‘24 a day before the event to advertise our IP solutions for PCIe 7.0, which resulted in a lot of extra traffic at our booth. All of the attendees were excited to see Cadence demonstrate the robustness of 128GT/s PCIe 7.0 IP's TX and RX capabilities over a real-world, low-latency, non-retimed, linear optics connector. We achieved and maintained a consistent, impressive pre-FEC BER of ~3E-8 (PCIe spec requires 1E-6) for the entire duration of the event, spanning over two full days with no breaks. This provides an ample margin for RS FEC. As seen in the picture below, the receiver Eye PAM4 histograms have good linearity and margin. This is the world’s first stable demonstration of 128 GT/s TX and RX over off-the-shelf optical connectors—by far the main attraction of DevCon this year.

Cadence 128 GT/s TX and RX capability over optics

Block diagram of Cadence PHY for PCIe 7.0 128 GT/s demo setup with linear pluggable optics

As a leader in PCIe, our PCIe controller architect Anish Mathew shared his valuable insights on an important topic: “Impact of UIO ECN on PCIe Controller Design and Performance,” highlighting the strides made by the Cadence design team in achieving this implementation.

Anish Mathew presenting “Impact of UIO ECN on PCIe Controller Design and Performance”

In summary, Cadence had a dominating presence on the demo floor with a record number of PCIe demos:

• PCIe 7.0 over optics
• PCIe 7.0 electrical
• PCIe 6.0 RP/EP interop back-to back
• PCIe 6.0 protocol in FLIT mode with Lecroy Exerciser (at Cadence booth)
• PCIe 6.0 protocol in FLIT mode (at the Lecroy booth)
• PCIe 6.0 JTOL with Anritsu and Tektronix equipment (at Tektronix booth)
• PCIe 6.0 protocol with Viavi Protocol Analyzer (at Viavi booth)
• PCIe 6.0 System Level Interop Demo with Gen5 platform (at SerialTek booth)

The Cadence team and its partners did a great job in coordinating and setting up the demos that worked flawlessly. This was the culmination of many weeks of hard work and dedication. Four different vendors featured our IP for PCIe 6.0. They attracted a lot of attention and drove traffic back to us.

Highlights of Cadence demos for PCIe 7.0 and 6.0

Cadence team at the PCI-SIG Developers Conference 2024

Thanks to everyone who attended the 32nd PCI-SIG DevCon. We really appreciate your interest in Cadence IP, and a big thanks to our partners and customers for all the positive feedback and for creating so much buzz for the Cadence brand.