Boot from SAN

program which is not needed. I believe OpenVMS does not page programs; it
reloads from the file.

Most OSes use memory mapped files to load binaries, and thus the code is never
swapped away.

--
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation

http://www.storagecraft.com

In article , "Tarjei T. Jensen" writes:
"Faeandar" wrote:
Every OS *can* page, doesn't mean they will. If you do not give it a
place to dump memory it will stay in memory. As long as my host has
enough memory to run all the things it needs to there is no need to
page memory out to disk.

It is OK if you have too much money. But most people will find that a
page/swap file will give the system the ability to use memory more
efficiently. There is less incentive if the system can discard parts of a
program which is not needed. I believe OpenVMS does not page programs; it
reloads from the file.


Actually.. in VMS, it depends. By default, this is the
behavior:

$ mcr sysgen help sys_param mmg_ctlflags

MMG_CTLFLAGS

MMG_CTLFLAGS is a bit mask used to enable and disable proactive
memory reclamation mechanisms. Beginning with OpenVMS Version
7.2, you can control when memory is tested. This helps reduce
the time between when you turn on the system and when you log in
to an AlphaServer 4100 computer. Bit 2 in the parameter controls
deferred memory testing.

The following bit mask values are defined:

Bit Description

0 Reclamation enabled by trimming from periodically
executing, but otherwise idle processes. This occurs when
the size of the free list drops below two times FREEGOAL.

1 Reclamation enabled by outswapping processes that have
been idle for longer than LONGWAIT seconds. This occurs
when the size of the free list drops below FREELIM.

===

What this means is when memory on free list drops below 2 x FREEGOAL
scan mostly idle process (not used CPU in last 30 seconds), trim that
process's working set by 25%. Proceed to do this until you have
2 X FREEGOAL pages on page list. By trimming only a portion of memory,
there is less impact when that process awakens to swap those
pages back in.

Things get really memory tight, behaviour then becomes SWAP entire
processes out when free list drops below FREELIM setting. And
at that target longwait idle processes (300 seconds idle).

Rob

"Tarjei T. Jensen" writes:

efficiently. There is less incentive if the system can discard parts
of a program which is not needed. I believe OpenVMS does not page
programs; it reloads from the file.

VMS does not page any read-only code or data. It is paged in from the
section file directly. In the case of program code, this is the program
file.

--
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+61 (08) 9257-1001 Kalamunda.
West Australia 6076
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