[Simh] Excessive paging of the real machine running SIMH - VAX

[Hittner, David T.]

Perhaps _flag was never initialized correctly, and the default
(uninitialized) values sometimes work and sometimes don't.
 
Dave

________________________________

From: simh-bounces at trailing-edge.com
[mailto:simh-bounces at trailing-edge.com] On Behalf Of Richard Davis
Sent: Tuesday, July 17, 2007 8:12 AM
To: simh at trailing-edge.com
Subject: [Simh] Excessive paging of the real machine running SIMH - VAX



Villy,

 

The issue only occurs on my system when first starting the system, i.e.
when the disks are first mounted, my disks are 1Gb and 2Gb
respectively.. 

A stack trace of the executable when the problem occurs shows the
following call trace:

 

sim_process_event

rq_svc

sim_fseek

fsetpos

_fseeki64

_fseeki64_nolock

_flush

_write

 

As mentioned before, the strange value in the _flag member of the stream
causes the _flush routine to do a complete flush of the disk file.

 

I modified the SIMH sim_fopen routine to use the _fsopen call (rather
than fopen) which allowed me to deny all sharing.. the problem still
occurs, so It's nothing to do with sharing!

 

I need to understand the workings of SIMH a bit better, and need to find
out how things are put onto the event queue (the _flag member is already
'corrupted' when the event gets processed in the sim_process_event
routine.

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