Linux 4.1 Has Improvements For The Multi-Queue Block Layer
For anyone not familiar with the kernel's new multi-queue block layer, you need to be reading more Phoronix. This code was added to Linux 3.13 and can lead to better disk performance with lower latencies by balancing the I/O workload across multiple CPU cores and also supporting multiple hardware queues. Since Linux 3.13, blk-mq has got into great shape and is delivering great performance.
For Linux 4.1, Facebook's Jens Axboe sent in the block core bits that have numerous blk-mq patches. In particular, there's an optimization for speeding up queue runs, blk-mq changes to support dm-mq, and cleaning up of blk-mq code. All the block core bits can be found via this pull request and there's also block driver updates.