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

[Richard Davis]

Ok, I've found out what the 0x80XX value means in the _flag member of the
FILE structure. it's an extended flag value which equates to _IOLOCKED which
is all to do with various stream routines being thread-safe - for other
definitions look in the VC CRT header file "file2.h".

 

So it seems that possibly, SIMH is trying to perform a stream operation on a
stream which may already be part way through a stream operation? Windoze
then seems to throw a complete wobbly and starts to perform a vast amount of
IO Writes.

 

Just to humour myself, I decided to replace all the calls to thread-safe
stream routines with calls to the _nolock routines.. bizarrely the same
event seems to occur (perhaps I missed one?!) with the stream being flagged
as locked.

 

How thread-safe is SIMH? Can anyone suggest any reasons why we seem to be
getting into this _IOLOCKED state? Perhaps Windoze is trying to be too
clever and is buffering stream operations? Or perhaps some strange Windoze
service is coming along and causing the file to be momentarily locked?

(Indexing service springs immediately to mind!).

 

Rich

 

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