I don't think we disagree, actually. Yes - from a purely technical point of view, DIO is superior in various ways. It allows tuning to specific I/O patterns, e

I don't think we disagree, actually. Yes - from a purely technical point of view, DIO is superior in various ways. It allows tuning to specific I/O patterns, etc. But it's also quite laborious to get right - not only does it require a fair amount of new code, but AFAIK there is significant variability between platforms and storage devices. I'm not sure the project had enough developer bandwidth back then, or differently - it was more efficient to spend the developer time on other stuff, with better cost/benefit ratio.