What is Infinity Fabric? (Explained)

What is Infinity Fabric?

Infinity Fabric refers to a system bus technology. It is used by AMD mainly in their Ryzen, Threadripper, and EPYC processors and Vega graphics.

Technically, Infinity Fabric is the successor to the AMD HyperTransport technology that can transfer data at a high speed between the processors, graphics cards, PCIe, I/O and memory modules.

KEY TAKEAWAYS

• Infinity Fabric is a proprietary bus technology or a system interconnect architecture of AMD that transfers data and control signals among all components that are linked to each other.
• This system architecture is included in several microarchitectures used in both CPUs and GPUs of AMD as well as in a few add-on accelerators.
• The data communication through this specific bus is typically controlled by the Infinity Fabric clock or FCLK.
• Infinity Fabric bus technology is made up of two communication planes such as Infinity Scalable Data Fabric and Infinity Scalable Control Fabric.
• The primary goal of this bus is to reduce data movement between the different components and thereby reduce the cost of it.

Understanding Infinity Fabric

Announced in December 2016 and launched first in February 2017 in the Ryzen processors, the Infinity Fabric HyperTransport technology initially had a data transfer rate of about 30 GB/s, which was later scaled up in the subsequent processor lines.

AMD’s Infinity Fabric provides a significantly improved method for accelerated system connectivity.

This technology actually pushes the limits of performance for x86.

Offering better security features and efficiency, the overall performance of the system is enhanced to support the higher computing needs of the next generation of enterprise data centers.

Apart from that, it also empowers the cloud architects as well as the system builders alike to improve server performance without compromising with manageability, power, or the most important asset – the data.

The main idea behind designing this bus technology is to reduce the cost of moving data.

This is typically done by reducing the movement of data between different storage banks as much as possible.

This technology ensures that every piece of the hardware in the computer system knows where exactly a particular information lies and can access it as and when required easily and quickly.

This offers huge performance gains.

What Does Infinity Fabric Do?

Infinity Fabric acts as a high speed link for interconnectivity for exchanging data between different connected components.

It helps to create a Heterogeneous System Architecture or HSA systems to facilitate intra-chip and inter-chip communication between different AMD CPUs and GPUs.

Typically, the Infinity Fabric allows communicating between different components of a computer which include:

• The Central Processing Unit or the CPU
• The Peripheral Component Interconnect Express or PCIe
• Input/Output
• Memory.

Its ability to facilitate intra-die data communications allows connecting different CPU Complexes or CCX with each other in the AMD Ryzen, EPYC, and Threadripper CPUs.

By acting as the connecting tissue for HPC and multi-chip modules, this bus technology improves HPC performance significantly by ensuring a more coherent data communication and transfer.

It also helps a lot in resource sharing between the CPU and GPU solutions.

Apart from boosting the performance, this feature also lowers power consumption and latencies.

What is the Infinity Fabric Clock?

The Infinity Fabric Clock of FCLK is that which controls the communication bus. It actually dictates the performance of the AMD processors because the data transfer through the bus is regulated by it.

The speed of this clock is directly related to the memory clock or MCLK and can be configured.

However, in the Zen and Zen+ processors it cannot be configured but is related to the speed of the Random Access Memory module of the system.

In such cases, higher performance is achieved when the frequency of the RAM is higher.

This clock has been however decoupled from the memory in and from the Zen 2 architecture and can be controlled separately from the system BIOS.

This ensures that the performance of the processor is not hampered even if the RAM amount of the computer system is low.

If it is an AMD Ryzen 3000 CPU, in most cases it will run at a ratio of 1:1 with the MCLK and up to 1800 MHz, which is considered to be a synchronous operation.

On the other hand, in a few situations, you can also set the Infinity Fabric clock at a different ratio than 1:1 so that it operates in an asynchronous mode.

However, this will increase the latency and therefore negate any performance benefits.

And, if the memory clock value is exceptionally high, such as in excess of 3,600 MHz, the asynchronous operation may increase the overall performance, but, as a matter of fact, it will do so at the expense of stability.

You may increase the speed of the Infinity Fabric clock, but that will come at a cost because it is not designed to be scaled too much.

If it is done you may encounter some issues such as increased system latency and blue screens due to de-synchronization in RAM latencies.

What is Infinity Fabric Made of?

This particular bus technology is typically made up of two distinct communication planes, namely, Infinity Scalable Data Fabric and Infinity Scalable Control Fabric, each playing a different role but for the same purpose of enhancing the overall performance.

Infinity Scalable Data Fabric:

Also known as SDF, it is the primary means of data flow between the different endpoints across the system. It may have a lot of connecting points that link different things such as:

• USB or Universal Serial Bus hub
• PCIe PHYs
• Memory controllers
• Different execution and computing units.

This is actually the superset of the earlier HyperTransport.

Infinity Scalable Control Fabric:

Also known as SCF, this is actually a complementary plane. It typically transfers a wide range of system control signals which include:

• Test signals
• Security signals
• Thermal and power management signals
• Third party IP.

With the help of these two planes, a lot of fundamental computing blocks can be scaled easily and more effectively by AMD.

What is Infinity Fabric Frequency?

Typically, the maximum frequency of Infinity fabric is reported to be up to 3000 MHz. However, this is just an option that you will see in the BIOS or Basic Input Output System setting. In reality, this frequency may not be achievable.

For example, for a memory with a speed of 3200 MHz, the frequency of Infinity Fabric may be set to 1600 MHz.

It will also maintain the 1:1 ratio with the frequency of the memory clock.

This offers the highest memory bandwidth and ensures the best memory latency possible.

Questions & Answers:

Conclusion

Infinity Fabric is the bus technology exclusive to AMD processors and graphics cards that facilitates data communication between different memory banks to enhance the overall performance.

This link to the CPU cores actually reduces the cost of moving data between different locations.