Barring any issues from coming up in the near future, it looks like DM-PCACHE will be submitted for the Linux 6.18 cycle later in the year as a high throughput, low latency cache for DAX-capable persistent memory devices.
Several months ago DM-PCACHE was submitted as a new persistent memory cache for block devices and originally designed for use with Compute Express Link (CXL) block devices. DM-PCACHE aims to be used in front of slower block devices by providing this high-throughput, low-latency cache. DM-PCACHE aims to have much lower latency than BCache while being similar to the DeviceMapper WriteCache. The stated performance of DM-PCACHE for random writes is said to be multiple times faster than either BCache or DM-WriteCache.
As of this week the DM-PCACHE persistent cache target was queued into the DeviceMapper’s linux-dm.git “dm-6.18” Git branch. Thus as long as no issues turn up, it should be submitted into the Linux 6.18 merge window in October.
