3 ms·

I actually was one of the people who did performance benchmarking of 3D XPoint before it came out. In app direct mode, you can maybe eek out 70% of the througho

I actually was one of the people who did performance benchmarking of 3D XPoint before it came out. In app direct mode, you can maybe eek out 70% of the throughout and about 3x worse latency. Also, not all apps support app direct mode. Many customers try to use 3D XPoint as another part of the cache hierarchy in-between regular ssd and ram. It's actually pretty neat for faas workloads which want containers to be "warm" rather than "hot" or "cold"...

wtallis 5y ago
To clarify for readers who aren't current on all the lingo: app direct mode refers to one of the modes for using the Optane persistent memory modules that connect to the CPU's DRAM controller. It doesn't apply to the Optane NVMe SSDs that use PCI Express and require the software overhead of a traditional IO stack. In a few years, something like CXL may allow for something close to the app direct mode to be usable on persistent memory devices with an SSD-like form factor, but we're not there yet.