CXL Memory Write Latency Testing With Non-Temporal Writes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing testing systems fail to efficiently and accurately measure write latency in Compute Express Link (CXL) compliant memory devices, particularly when testing multiple devices in parallel, due to the CXL protocol being primarily designed for normal computer use rather than testing environments.
Innovation Solution
A system and method for measuring write latency by using a motherboard with a processor and external memory devices, where write operations are recorded in a frequency table, and the results are visualized, allowing for accurate latency determination through counter measurements and overhead subtraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the CXL protocol is used for normal computer use of external memory devices, then the devices can function as additional shared main system memory resources, but the protocol is not optimized for testing environments and cannot efficiently test multiple devices in parallel
Solution Approach 1:
The system segments the testing process by assigning dedicated test controllers to each CXL memory device under test. Each test controller independently manages test operations for its assigned device, enabling parallel testing while maintaining protocol compliance. This segmentation allows the system to overcome the CXL protocol's lack of native parallel testing support.
Solution Approach 2:
Test controllers serve as intermediary components between the test system and CXL memory devices. These intermediaries translate standard CXL protocol operations into test-specific commands, enabling efficient testing without modifying the underlying CXL protocol. The test controllers mediate between the protocol's normal operation mode and testing requirements.
2Measurement precision
If traditional Automatic Test Equipment (ATE) is used to measure write latency, then testing can be performed, but the measurement is not accurate or efficient for CXL system memory
Solution Approach 1:
The test system utilizes the CXL memory devices' own operational characteristics and protocol mechanisms to perform self-testing. Write latency is measured by exploiting the natural write operation flow through the CXL protocol, allowing the system to accurately measure latency without requiring complex external timing instrumentation or modifying the devices under test.
Solution Approach 2:
The system changes the operational parameters of the CXL protocol during testing modes compared to normal operation. By adjusting timing parameters, data transfer sizes, and test-specific protocol extensions, the system achieves accurate write latency measurement while maintaining compatibility with standard CXL operations. This parameter adjustment enables precise measurement without increasing overall system complexity.
3Quantity of substance
If external memory devices are coupled to the system board via CXL protocol, then additional shared storage resources are provided, but write latency measurement becomes problematic in test system environments
Solution Approach 1:
The system performs preliminary configuration and calibration of test parameters before actual write latency measurement. Test controllers pre-establish timing references, configure memory addresses, and prepare data patterns before initiating write operations. This preliminary action simplifies the measurement process by ensuring all conditions are optimized before the actual latency-critical write operation occurs.
Solution Approach 2:
The system implements feedback mechanisms where write acknowledgment signals from CXL memory devices are captured and analyzed by test controllers. This feedback loop provides real-time information about write operation completion, enabling accurate latency calculation. The feedback mechanism transforms the CXL protocol's normal acknowledgment flow into a measurement tool, making write latency detection straightforward despite the protocol's original design for storage expansion.
Data Source
AI summary
The testing system comprises a processor and a local memory on a motherboard and an extension memory device under test (DUT). The local memory corresponds to a first address range within system memory and the extension memory DUT associated with a second address range within the system memory. The processor is operable to direct write latency testing of the extension memory DUT, including recording write latency measurement values. The recording can be done in a frequency table and the frequency table can be visualized (e.g., rendered, etc.) on a display. The testing comprises non-temporal write instructions that bypass processor caches. The extension memory DUT is compatible with a compute express link (CXL) protocol.