[6227] in linux-scsi channel archive
RE: IDEA: multiple dirty lists in buffer.c
daemon@ATHENA.MIT.EDU (Kai Harrekilde-Petersen)
Wed Mar 31 01:55:48 1999
From: Kai Harrekilde-Petersen <KHP@olicom.dk>
To: Linux <linux-kernel@vger.rutgers.edu>, linux-scsi@vger.rutgers.edu
Date: Wed, 31 Mar 1999 08:46:10 +0200
> From: Gerard Roudier [mailto:groudier@club-internet.fr]
>
> On Tue, 30 Mar 1999, Rik van Riel wrote:
>
> > On Mon, 29 Mar 1999, Gerard Roudier wrote:
> > > Basically, for SCSI disks, using for example 8 dirty lru lists and
> > > the following hash: [SNIP]
> >
> > But why would we ever want to use an LRU list for write-outs?
>
> Because we are unable to ask applications about buffers that will be
> rewritten soon and those that will not. ;-)
>
> The LRU is just some minimal and simple aging heuristic that
> can be used
> when we have no other info about the relevance of caching or
> not. It is
> usually better that just random and fairly simple.
</lurk>
I am in no way an expert on the kernel, but the discussion about
ordering just made this pop into my head: Have you considered
multi-disk partitions (ie: raid systems)? - I assume that the current
single-dirty-list design does some "default" ordering between the
disks, which is necessary for multi-disk partitions, and the
dirty-list-per-disk design might remove it without realizing it.
<lurk>
Kai
--
Kai Harrekilde-Petersen <khp@olicom.dk> #include <std/disclaimer.h>
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