[Simh] Slow VMS I/O

[Villy Madsen]

Disks are rauser=2048 and 4096

Yes - I always shutdown properly

found the following in fcntl.h of the w/2003 platform sdk

I don't know if it means anything, but I thought it was interesting.....

#ifndef _CRTBLD
/* This version of the header files is NOT for user programs.
 * It is intended for use when building the C runtimes ONLY.
 * The version intended for public use will not have this message.
 */
#error ERROR: Use of C runtime library internal header file.
#endif  /* _CRTBLD */

#define _O_RDONLY       0x0000  /* open for reading only */
#define _O_WRONLY       0x0001  /* open for writing only */
#define _O_RDWR         0x0002  /* open for reading and writing */
#define _O_APPEND       0x0008  /* writes done at eof */

#define _O_CREAT        0x0100  /* create and open file */
#define _O_TRUNC        0x0200  /* open and truncate */
#define _O_EXCL         0x0400  /* open only if file doesn't already exist */

/* O_TEXT files have <cr><lf> sequences translated to <lf> on read()'s,
** and <lf> sequences translated to <cr><lf> on write()'s
*/

#define _O_TEXT         0x4000  /* file mode is text (translated) */
#define _O_BINARY       0x8000  /* file mode is binary (untranslated) */


----- Original Message -----
From: bsupnik at comcast.net
Date: Tuesday, July 17, 2007 8:41 am
Subject: [Simh] Slow VMS I/O
To: simh at trailing-edge.com

> <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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> Simh at trailing-edge.com
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> 
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