I/O Interfaces & Buses
What is an advantage of memory expansion using CXL (CXL memory)?
- ALatency is always lower than DRAM attached directly to the CPU
- BData is always retained when power is off
- CCapacity can grow beyond the limit of the CPU's memory channels, and memory can be pooled among servers
Show answer and explanation
Answer: C. Capacity can grow beyond the limit of the CPU's memory channels, and memory can be pooled among servers
The memory attachable directly to a CPU is capped by its number of memory channels and slots. CXL memory adds capacity by attaching memory devices to PCI Express slots or similar, and with switches several servers can share pooled capacity. Its latency is higher than directly attached DRAM, though, so it is used as a tier, with frequently used data kept in direct memory.
- A. The longer path makes latency higher than directly attached DRAM.
- B. The media is usually ordinary DRAM, not necessarily non-volatile.
- C. Correct. It allows flexible expansion and sharing.