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use_virtual_scratch_files@ available for ftn95?

 
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DietmarSiepmann



Joined: 03 Jun 2013
Posts: 179

PostPosted: Tue Feb 12, 2019 5:15 pm    Post subject: use_virtual_scratch_files@ available for ftn95? Reply with quote

Hello,

in Salford's ftn77 environment there was a call to enable or disable the virtual scratch file facility, namely
Code:

use_virtual_scratch_files@

. If the virtual scratch file facility was enabled, files opened with STATUS='SCRATCH' were never written to disk but held in virtual memory.

Now, I could not find use_virtual_scratch_files@ in Salford's ftn95 compile environment.

Hence I would like to know, if the virtual scratch file facility is available under ftn95, and if so, by which call I would enable or disable it.

Thanks,
Dietmar
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PaulLaidler
Site Admin


Joined: 21 Feb 2005
Posts: 6092
Location: Salford, UK

PostPosted: Sun Feb 17, 2019 6:30 pm    Post subject: Reply with quote

I can't find any reference to scratch files that are "virtual".

There are routines for mapping files to memory such as MAP_FILE_FOR_READ_WRITE@ but I have not looked up the details.
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LitusSaxonicum



Joined: 23 Aug 2005
Posts: 2055
Location: Yateley, Hants, UK

PostPosted: Mon Feb 18, 2019 12:11 pm    Post subject: Reply with quote

Paul,

It's in the FTN77 library manual, available on this website. If it never migrated from FTN77 to FTN95, and given that it seems so sensible, isn't there a case for resurrecting it?

Eddie
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JohnCampbell



Joined: 16 Feb 2006
Posts: 2145
Location: Sydney

PostPosted: Wed Feb 20, 2019 3:23 am    Post subject: Reply with quote

As most disk I/O is now buffered, why worry about virtual files; disk files would probably give similar performance.
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John-Silver



Joined: 30 Jul 2013
Posts: 1232
Location: Aerospace Valley

PostPosted: Fri Feb 22, 2019 9:07 am    Post subject: Reply with quote

I detect (as an amateur) confusion as to what 'virtual' means.
Confusion is oft brought about by a lack of clear definition.

First there's memeory. Real physical memory.

Second there's 'virtual' memory which, to me anyway, means storing stuff somewhere which is not real physical memory but ON A DISK somewhere, and then bringing it into and shoving it out of real memory. Quickly.

Scratch files are traditionally fėthe files which facilitate this

We used to call it paging.

The terminology 'Scratch files' are traditionally fėthe files which facilitate this

(there's probably something somewhere these days called 'viėrtual paging' no doubt !) Just to add a layer to the confusion.

Well, there's 'virtual scratch files' which is being discussed, but how the 'eck it relates to eality is beyond me.

This discussion seems to think there's some other 'location' available.

Maybe I'm just confused.

Maybe it's something they have on the starship enterprise.

Maybe I just have to RTFf77M

Clarification is needed.

Over to yee Cp't'n, Bones and Scottie
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