The MD subsystem updates were sent out earlier this week for the Linux 4.9 kernel merge window with a few improvements/features to note.

The MD RAID code for the Linux 4.9 kernel has some optimized functions making use of AVX512 extensions for RAID6 gen/recovery, the non-rotational bit is set when creating a RAID array with all SSDs, and setting the correct max_hw_sectors for RAID 5/6 modes should marginally improve the performance.

The MD code for Linux 4.9 also fixes a potential deadlock, a couple md-cluster bugs, and some other minor fixes.

More details on the MD updates for Linux 4.9 via this pull request.