disksort() with swapdev

[Don Speck]

In article <615 at philmds.UUCP>, hulsebos at philmds.UUCP (Rob Hulsebos) writes:
> I think it would be more efficient if any I/O to be done on swapdevices
> is given preference above 'normal' I/O, which can be done if disksort()
> checks for it, and inserts the swap I/O requests at the head of the queue.

Why not take this further, and let I/O that some process is waiting for
take priority over B_ASYNC bufs, which nothing is waiting for?	This way
page-ins and blocking reads would take precedence over readahead and
writebehind blocks, improving response time.

The CPU scheduler assigns priorities, why shouldn't the disk scheduler?

Don Speck   speck at vlsi.caltech.edu  {amdahl,ames!elroy}!cit-vax!speck