QPI Is Cool…

Many of us are responsible for validating and testing Intel®-based designs. The latest Intel® Xeon® and Itanium® processor platforms use Intel’s QuickPath Interconnect (QPI) to tie the processor and the I/O hubs together into single, dual, and multi-processor systems. ASSET got a nice promotion in Intel’s book on QPI: “Weaving High Performance Multiprocessor Fabric: Architectural Insights into the Intel QuickPath Interconnect”.

For those who might be interested in the book, it’s available for about $80 from www.amazon.com. On pages 257-259, Intel talks about the ASSET ScanWorks® IBIST (Interconnect Built-In Self Test) tool. To quote:

“ASSET InterTech, Inc. has collaborated with Intel Corporation to create a product known as the ScanWorks IBIST Toolkit. This toolkit can control the execution of tests on several interfaces including Intel QPI. It does this by exercising the built-in pattern generation and checking functions of the devices. User-defined patterns or component-created pseudo-random patterns can be driven and checked at the full operating speed of the link. This is done under the same interconnect channel characteristics that the platform will use in normal operation. No additional probing is added to the link circuits. The toolkit works by accessing functions of the devices through the JTAG test access port. With this pattern generation and checking testing, the link’s basic connectivity and data integrity can be checked.

For more in-depth bit error rate (BER) testing, the toolkit can kep track of the total bits transferred and the total error count. This allows a computation of the observed BER for that link. Furthermore, the toolkit can modify equalization settings at the transmitter, and introduce voltage and timing offsets at the receiver while the tests are underway. In this manner the tool can build up a representation of the received data eye diagram – at speed and in system. This allows the user to identify relative receiver performance margins for the platform under test.”

Thanks Bob, Gurbir and Rob!

Still interested in learning more about QPI? Have a look on the MindShare’s website: www.mindshare.com. Although I’ve personally never taken one of their classes, I’ve heard good things about their material; they are Intel’s training partner and have a lot of interesting courses covering various topics such as x86 assembly language, Intel® Atom™ microarchitecture, QPI, PCIe and USB 3.0 technology, and so on.

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