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From: Terry Lambert <tlambert@primenet.com>
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Subject: Re: Bumping up {MAX,DFLT}*PHYS (was Re: Bumping up {MAX,DFL}*SIZ in i386)
To: phk@critter.freebsd.dk (Poul-Henning Kamp)
Date: Tue, 6 Feb 2001 02:48:19 +0000 (GMT)
Cc: gibbs@scsiguy.com (Justin T. Gibbs),
	bright@wintelcom.net (Alfred Perlstein),
	rjesup@wgate.com (Randell Jesup),
	dillon@earth.backplane.com (Matt Dillon),
	mjacob@feral.com (Matthew Jacob), msmith@FreeBSD.ORG (Mike Smith),
	des@ofug.org (Dag-Erling Smorgrav),
	dnelson@emsphone.com (Dan Nelson),
	tanimura@r.dl.itc.u-tokyo.ac.jp (Seigo Tanimura), arch@FreeBSD.ORG
In-Reply-To: <29299.981412612@critter> from "Poul-Henning Kamp" at Feb 05, 2001 11:36:52 PM
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> >It doesn't have to be a simple call if it only occurs once on mount
> >and whenever a component makes an async upcall telling the system that
> >its state has changed (array is degraded, or perhaps commonly accessed
> >data has migrated to a different striping or RAID layout).
> 
> I think we are talking too many different things at the same time here.

Way too many irons in the fire here...


> The upcall I (and I belive Alfred) were discussing were happening
> once per I/O.

I don't think an upcall is really useful.  Given a stack of things,
possibly including Vinum and friends, it would be really difficult
to get the event propagation semantics right, in any case.  It only
gets worse, with vnode devices and FS stacks.


> The one you are talking about is obviously the one to formulate an
> abstract clustering preference for a device ? 

I still think it might be worthwhile to readdress the seek minimization
code, by reading mode page 2 on SCSI drives, and using the knowledge of
the real seek boundaries.  Your point about whiling away Winter nights
is well taken.


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.


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