Subject: Re: pages.
To: Rob Healey <>
From: None <>
List: amiga-dev
Date: 03/20/1994 12:45:58
> 	Markus, we both know the real reason for the AmigaUNIX I/O sucking
> 	is the terrible SCSI and inturrupt system. The page size is a drop
> 	in the bucket compared to the other glaring deficiancys.

Don't think the page size can be ignored.. I did some experiments on SVR4
trying to recombine pages submitted to the scsi driver, as long as they
were contigous. Improvement was quite noticeable. Problem is, this
wasn't always possible as page-in requests came in 2k chunks, and I could
just be lucky if I could recombine 4 such requests into 1 8k job.

> 	You call pissing away 1M of memory a "slight" waste of memory!?!?!?
> 	I'd call that a big fork()ing memory PIG!

Eh, I didn't get Chris' message that way.. He said he wanted to overall improve
the (memory) efficiency of pmap, which I think, is a real good idea. Having
4k instead of 8k pages is one aspect of this research. Keep in mind that 
page tables of not running processes don't HAVE to be in physmem, it's not
legitimate to multiply small losses of single process page tables by the
number of processes to get to exorbitant losses of physmem.

> 	With an IDE driver and the ability to comfortably run in 4M of
> 	fast I think we would all be pleased at the number of new NetBSD
> 	people we could pick up. We all know the more people involved
> 	the better it is.

*comfortly* run in 4M? come on.. hey, I worked with a PC linux with 4M,
and that's in no way a comfortable way to work.. unless you enjoy watching
your harddisk page all the time when editing...

> 	I agree about ZorroIII, it should be a part of the new pmap design.
> 	The hp300 and Mac people would be fools to waste 1M of memory

Again, I don't think the sole difference of 4k to 8k pages will give you
back 1M.

> 	So, let's get to the REAL reason you don't want a 4k page size:
> 	It would mess up SunOS emulation!

I don't think it would have to. Returning a different page size when running
as a SunOS process might already do. What I care for is performance, and
I believe it to be better with 8k than 4k pages, nothing more.

> 	This is NetBSD, NOT SunOS DAMNIT! Why should we braindamage NetBSD

Sure. But you don't want to nuke the emulation because of that, do you? 

> 	for a dead OS like m68k SunOS? I see no good reason for it. The only

SunOS is far from dead, considering the 2$#@$@ problems everyone has running
Solaris.. as long as Sun can't provide an equally stable OS as SunOS, lots
of people that don't HAVE to "upgrade" to Solaris, won't. (Still running
all but one Sparc on 4.1.3, and the only reason one machine has to run
Solaris is to run the ISDN software that doesn't run under 4.1.3:-(()

> 	I think it is MUCH more valuable to bring in more Amiga owners and
> 	bring in POSIX features than to try to keep compatable with a dead OS
> 	like m68k SunOS.

Why can't be do all of them? Improving pmap keeping 8k pages should be just
as winning.

CHUUG/EUnet Switzerland				Markus Wild
Zweierstrasse 35	Tel: +41 1 291 45 80
CH-8004 Zuerich		Fax: +41 1 291 46 42	S=mw;P=EUnet;A=EUnet;C=CH