[Simh] trouble with idle detection on VAX

[Villy Madsen]

It appears to me that windows is handling IO the same way that VMS does for memory mapped IO.  I think that what is happening is that Windows isn't sure where the end of the file is, so it reads the entire file to find the end....

- it is mapping it to virtual memory, but that virtual memory is backed up by that file, not the windows swap file...

I think

Villy

----- Original Message -----
From: Michael Unger <unger at decus.de>
Date: Tuesday, June 12, 2007 8:43 am
Subject: Re: [Simh] trouble with idle detection on VAX

> On 2007-06-12 15:42, "Villy Madsen" wrote:
> 
> > [...]
> > 
> > I am still finding that there is still something strange going on
> > when mounting VAX disks (running under XP).  What I think is
> > happening is that Windoze is sometimes mapping the entire disk
> > into memory (a la Noncontiguous Shared Segment <G> anyone
> > recognize that term).  When that happens, windows reads every
> > byte on the virtual disk before VMS can mount it...
> > 
> > That could be the source of the slow boot-up of VMS (if you are
> > running under windows)
> 
> There *might* be a simple explanation for this: What is an entire 
> *disk*for VMS is a *single* file for Windows, and perhaps it just 
> tries to
> "cache" this file -- which usually doesn't fit into RAM so the 
> page file
> is accessed as well.
> 
> > [...]
> 
> Is there any possibility to open these "container files" _uncached_?
> 
> Michael
> 
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