Changing Page Size

[Jim Hintze]

While fully understanding that OpenVMS can not understand any page size other than 8192, How does one change the page size to a value other than 8192. Alpha ES45/ES40 answers are also welcome.

thanks
Jim

[Jozef_Novak]

Hi Jim,

this is a question for OpenVMS forums, I believe.

J.

[Jim Hintze]

Sorry I wasn't clear on the first post. this is an operating system independant question.

on either integrity (2660, 6600, 8640) or alpha (es40/es45), how does one change the page size?

thnaks
Jim

[Torsten. · Accepted solution]

Isn't it a kernel related setting?

From my hp-ux box:

# getconf PAGESIZE
4096

# kmtune -q vps_pagesize
Parameter Current Dyn Planned Module Version
===============================================================================
vps_pagesize 4 - 4


So it is not hardware related ;-))

See also (for hp-ux):

http://docs.hp.com/en/B3921-90010/vps_pagesize.5.html

[Jim Hintze]

OK, conflicting info from another forum.
spot on, Thanks.

[Andrew C Fieldsend]

The processor's Translation Lookaside Buffer (TLB) implementation defines the allowable values for the page size (see the relevant processor documentation for the details), but the operating system memory management code determines which values are actually used.

Actually, OpenVMS can understand other page sizes than 8k, but 8k is the default. See section 12.1 of the OpenVMS Programming Concepts Manual at http://www.openvms.compaq.com/doc/82final/5841/5841pro_038.html.

So it's both a hardware and operating system question;-)

[Jim Hintze]

looking in circles here??

BOO$GQ_PAGE_SIZE = .HWRPB[HWRPB$IL_PAGESIZE_L];

MMG$GL_PAGE_SIZE is filled from BOO$GQ_PAGE_SIZE

while VMS may have the capacity to understand different values for BOO$GQ_PAGE_SIZE, Do I have the opportunity to set it anywhere??

[Andrew C Fieldsend]

After some searching, I've found that the page size is set from the HWRPB (as you pointed out). The HWRPB is set up by the boot firmware, so if it is modifiable this will be the only place to do it - though I suspect it will be hardcoded in the firmware for each system, as it needs to be configured early in the boot process.