topic Re: Pages or pagelets in Operating System - OpenVMS

Pages or pagelets

Thomas A. Williams — Fri, 30 Jan 2009 20:24:19 GMT

I know this is a dumb question, but I need to be sure: When I do a "show process/accounting", what are the units for "peak working set size" and "peak virtual size"? Pages or pagelets? I assume it's the same as what's in accountng.dat. Thanks

Re: Pages or pagelets

Robert Gezelter — Fri, 30 Jan 2009 21:12:30 GMT

Thomas,

The answer is that SHOW SYSTEM is actual hardware pages. AUTHORIZE, SET WORKING_SET and others work in pagelets (universal quantum; aka VAX page size).

A quick check with my cellphone (calculator mode) on the ACME process (Alpha 6.2) and cross checked with SHOW SYSTEM indicates that SHOW PROCESS/ACCOUNTING is displaying in pagelets.

- Bob Gezelter, http://www.rlgsc.com

Re: Pages or pagelets

John Gillings — Sun, 01 Feb 2009 20:53:01 GMT

Thomas,

Definitely NOT a dumb question! Different utilities and displays use the two units interchangebly, often without any clear indication. It's very confusing!

Unfortunately there are no simple rules to remember which is which. You just have to know each context :-( It helps that it's an order of magnitude difference, so often you can tell the difference by sanity check.

That said, in general, things which are VAX heritage, or can potentially be physically shared across a cluster (like ACCOUNTNG and AUTHORIZE) tend to use the generic unit (pagelets). Things which are node specific (like SHOW SYSTEM) sometimes use physical pages.

To add to confusion, SYSGEN uses physical units internally, but displays generic units, or both.

If in doubt, try SET PROCESS/UNIT=BYTES. For some things this will change the display units to absolute bytes which are unambiguous.

(if only VMS engineering had chosen a page to be 1KB way back then, this would be less of an issue. Another burden we have to bear because of the historic price of storage!)

Re: Pages or pagelets

Thomas A. Williams — Mon, 02 Feb 2009 17:32:54 GMT

Thanks for the excellent info! I hate to say it, but this forum is much better at getting a "straight answer" to these types of questions than by calling HP support. To be fair, once you get a "real guru" on the line, it's not that bad, but gettingt to point is excruciating.

Re: Pages or pagelets

Thomas A. Williams — Mon, 02 Feb 2009 17:34:16 GMT

As always, the Forum is the place to go for "no-nonsense" and quick! answers to questions.