Xref: utzoo comp.unix.wizards:11076 comp.unix.questions:9174
Path: utzoo!attcan!uunet!husc6!bloom-beacon!oberon!cit-vax!mangler
From: mangler@cit-vax.Caltech.Edu (Don Speck)
Newsgroups: comp.unix.wizards,comp.unix.questions
Subject: Re: disksort() with swapdev
Summary: B_ASYNC
Keywords: disksort, swap devices, disk I/O
Message-ID: <7923@cit-vax.Caltech.Edu>
Date: 12 Sep 88 08:57:25 GMT
References: <615@philmds.UUCP>
Organization: California Institute of Technology
Lines: 13

In article <615@philmds.UUCP>, hulsebos@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@vlsi.caltech.edu  {amdahl,ames!elroy}!cit-vax!speck