topic Re: change memory page size in Operating System - OpenVMS

change memory page size

Winfried Wetzel — Tue, 27 May 2008 15:34:41 GMT

normaly the memory page_size on I64 is 8K.
I found in some docu that this parameter is variable from 4K up to 4GB.
How can i change the page_size.

Re: change memory page size

Hoff — Tue, 27 May 2008 15:45:36 GMT

The literal answer to your question presently involves re-writing or re-working parts of the OpenVMS bootstrap and OpenVMS memory management implementation.

The Granularity Hints mechanisms might be of interest, depending on what you're up to.

Put another way, OpenVMS is (currently) operating with eight kilobyte page size. Simply because underlying Alpha or Itanium processor hardware or the architecture might support a feature does not mean that the operating system supports same.

What might you be up to here?

Re: change memory page size

Hein van den Heuvel — Tue, 27 May 2008 17:54:36 GMT

The hardware for I64 will support various page sizes, but OpenVMS will not. It has picked 8KB for you.

Is there a particular problem you hope to solve, or is this a curiosity question?

Using "reserved memory" one can share Page Table Entries and reduce the number of translation buffer entries needed, similar to large pages.

Google for: +openvms "granularity hints" "reserved memory"

http://h71000.www7.hp.com/doc/82FINAL/5841/5841pro_048.html

Hope this helps some,
Hein van den Heuvel
HvdH Performance Consulting