[Simh] Slow VMS I/O

[Brian Knittel]

what version of the C compiler are you using where you
see these unexpected flag values? I have several
versions of MSVC and in most of them the source code
for the C libraries is supplied, so we can look to see
what stdio does with _flag. If that would be helpful.

Brian

On 17 Jul 2007 at 14:40, bsupnik at comcast.net wrote:

> <snip>
> As far as I'm aware (please correct me if I'm wrong), the _flag member
> should only ever hold an 8 bit value (even though the member is an int in
> size) as defined by the _IO definitions in stdio.h 
> 
> On the occasions that the excessive paging/disk accesses occur I have seen
> the _flag member hold 0x80XX, where the XX is one of the normal stream
> states, to my way of thinking it looks like something might be trying to
> reset the _flag member to _IORW but somehow is writing to the upper 8 bits
> of the member???!
> <snip>
> 
> I ran through a complete boot sequence on VMS, and I never saw the _flag member assume any value other than 00XX.  That is, I never saw the 80XX flag set.
> 
> I am using Visual Studio C++ 2005... but I also use relatively small disks (RD54's).
> 
> Questions for Villy, since Richard has seen the same symptoms with big disks.
> 
> 1. What size disks are you using?
> 2. Are they standard disks, or custom size disks?
> 3. Do you shut VMS down cleanly when you stop simulating?
> 
> /Bob Supnik
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_| _| _|  Brian Knittel
_| _| _|  Quarterbyte Systems, Inc.
_| _| _|  Tel: 1-510-559-7930
_| _| _|  http://www.quarterbyte.com