Subject: Re: NetBSD 1.6 Release Schedule
To: Manuel Bouyer <bouyer@antioche.lip6.fr>
From: Wojciech Puchar <wojtek@chylonia.3miasto.net>
List: port-i386
Date: 06/20/2002 13:19:51
> > > it's not that large). The problem is that when you have several 10s
> > > of MB in the queue to be written, it takes several seconds for the queue to
> > > drain. As the queue is mostly FIFO, new requests are delayed for several
> > > seconds.
> > i understand. can't we have 2 queues?
>
> This is what I'm saying since the begining :)
> Yes, we need to give different priorities to different I/O, and having several

exactly. in simplest case one queue for reads, one for writes.

then making request in 1:1 method for drives with write cache (drive will
then order reads and writes in good sequence).

and timeslice method for drives that haven't (for example execute one
queue for no more than 100ms, more time means less seeks, less time
means shorter stalls).

> queues one way to do this (it may not be the best; if we want to keep disksort
> keeping a single queue may be easier). The problem is to define the

i think we can have disksort for each of 2 queues. read above