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EXT4 Changes Land In Linux 5.10 With Fast Commits, Big Boost For Parallel Writes
As noted previously, there is a big optimization for file overwrites when in DAX/DIO modes for EXT4 such as when running off Intel Optane DCPMM storage.For parallel writes in such scenarios -- particularly random overwrites -- there can be upwards of a 10x performance improvement or a 2x performance improvement in more basic areas. But you must be using the EXT4 iommap code such as in the DAX/DIO modes with this change not affecting conventional operation of EXT4.
Another big change is the new EXT4 "fast commits" mode by Harshad Shirwadkar of Google. This fast commit mode is relevant for EXT4 users operated in ordered mode (the mount option data=ordered) and maintains a minimal delta for recreating the affected metadata in the fast commit space shared with the JBD2 journal. That can yield up to a ~103% write performance improvement in the ordered mode with fast commits enabled.
The EXT4 changes also include other fixes and low-level code improvements.