Core Concepts of Shared Memory with CXL Quiz

Explore foundational knowledge about Compute Express Link (CXL) and its shared memory capabilities, essential for interviews and computer science basics. This quiz covers architecture, protocols, use cases, and key concepts with easy questions.

1. CXL Shared Memory Basics

   Which feature does CXL enable that differentiates it from traditional PCIe in memory systems?

   1. Faster CPU clock speeds
   2. Direct USB data transfer
   3. Coherent shared memory access
   4. Exclusive GPU interconnects

   Explanation: CXL allows coherent shared memory access between devices, which traditional PCIe does not provide. Faster CPU clock speeds are not a direct feature of CXL, exclusive GPU interconnects refer to other technologies, and direct USB data transfer is unrelated.

2. CXL Protocol Layers

   What protocol does CXL use as its physical transport layer?

   1. Ethernet
   2. PCI Express
   3. HyperTransport
   4. NVLink

   Explanation: CXL uses PCI Express (PCIe) as its underlying physical transport, leveraging existing hardware. Ethernet is used in networking, NVLink is a different interconnect, and HyperTransport was used in older AMD systems.

3. Use Cases of Shared Memory

   In which scenario is CXL shared memory particularly useful?

   1. Enhancing keyboard input
   2. Increasing hard drive speeds
   3. Expanding memory pools between CPUs and accelerators
   4. Lowering video display lag

   Explanation: CXL shared memory is designed to allow memory resources to be efficiently shared between CPUs and accelerators. It does not impact hard drive speeds, keyboard input, or video display lag.

4. CXL Device Types

   Which of the following is a type of device commonly supported in a CXL shared memory system?

   1. Printers
   2. Monitors
   3. DVD drives
   4. Memory expanders

   Explanation: Memory expanders are a key device type for CXL shared memory implementations, allowing additional RAM to be added. DVD drives, printers, and monitors are not involved in shared memory systems or CXL connectivity.

5. CXL and Data Coherency

   Why is data coherency important in CXL shared memory systems?

   1. It extends the lifespan of SSDs
   2. It increases screen brightness automatically
   3. It improves internet download speed
   4. It prevents data corruption when multiple devices access the same memory location

   Explanation: Data coherency ensures all devices see the most recent value of a shared memory location, preventing corruption and inconsistencies. It is unrelated to display brightness, internet speeds, or SSD lifespan.