Path: utzoo!mnetor!uunet!nuchat!sugar!karl
From: karl@sugar.UUCP (Karl Lehenbauer)
Newsgroups: comp.sys.amiga
Subject: Re: simple AmigaDos thrashing solution
Message-ID: <1505@sugar.UUCP>
Date: 2 Mar 88 00:57:27 GMT
References: <8504@sunybcs.UUCP> <1177@goanna.oz> <107@boing.UUCP> <5282@well.UUCP>
Organization: Sugar Land UNIX - Houston, TX
Lines: 34

In article <5282@well.UUCP>, ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab) writes:
> In article <107@boing.UUCP> dale@boing.UUCP (Dale Luck) writes:
> >The trackdisk driver as originally written did have more than 1 track
> >buffer. We had to limit it to 1 though to keep all those 265k
> >systems working.  Maybe it is time to rethink this strategy and let it
> >loose again.  [ ... ]

Perhaps number of trackdisk buffers could be settable.  Two drive systems
would be incredibly faster if the number could be set to, say, 320.
(no smiley - it's only 1760k bytes after all, not outrageous in the modern
era)

> 	Personally, I'm a believer in functional seperation.  IMHO, the
> trackdisk.device should not be trying to second-guess the guy making
> requests of it.  Its sole responsibility should be to get them bits off the
> media and into memory.  It should also know how to move the head around so
> it can find them bits.

I agree that trackdisk.device should not try to understand or interpret 
the contents of the data at a logical level higher than as a bunch of bytes.

...and if you're *not* saying that the filesystem shouldn't cache whole
tracks, I take no issue.

But I think that, if one has enough memory, caching at the track level
is a major performance win, because it will always end up with more
data in the cache, sooner, than any higher-level kind of caching that
would not be putting everything it got from trackdisk.device into the cache.
(...pity the filesystem wasn't designed to take advantage of the track-at-a-time
characteristics of the drive hardware.  On the other hand, tieing the OS
too closely to the hardware causes problems later - like with hard disks.) 
-- 
"Lack of skill dictates economy of style." - Joey Ramone
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