RE: What About Price vs. Performance?

["M. Lazarus" <mlazarus@xxxxxxxx>]

John,

At 4/4/01 08:14 AM -0400, you wrote:
>2.  OS/400 (and the Sys/38 before it) had algorithms at the heart of it's
>design that would page out pages of memory on a "by recent use" algorithm.
>We used to have Purge(*yes) and Purge(*no) for our call stack variables.
>Now it all works like Purge(*no) meaning that most recently used pages of
>memory are left there and only written to disk when space is needed and
>that page has not been marked as having been used recently.

1)  Does this mean that the PURGE() is now ignored (or unavailable)?

2)  My understanding of how PURGE() works differs from you 
explanation.  PURGE( *YES ) allows the system to page *part* of your 
program to disk as needed.  PURGE( *NO ) forced the system to page the 
*entire* program out, if the memory space is needed.

  Typically, an interactive program would be set to PURGE( *YES ), since 
only one section of code tends be needed during a given time span (i.e. 
processing of one screen at a time.)

  A batch program would usually not benefit from getting paged out in 
pieces, so it makes more sense to do it all at once.

  Comments?

  -mark

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