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Status Delivered
Workspace AIX
Created by Guest
Created on Mar 10, 2022

Add an AIX linker option to specify SHMPSIZE

As discussed in the Support case TS008099503, the ISV would like to be able to specify not only DATAPSIZE, TEXTPSIZE and STACKPSIZE as a linker option but also allow SHMPSIZE to be specified.

Currently, if you build an application which should use 64K pages to improve runtime performance, you can set the LDR_CNTRL at runtime to "DATAPSIZE=64K@TEXTPSIZE=64K@STACKPSIZE=64K@SHMPSIZE=64K".
Setting the environment variable before starting the application is a user action that is often times 'forgotten' - leading to degraded performance of the application.
As an alternative, the use of 64K pages can be built-in the application by specifying it as a linker option.

But currently, the linker only accepts 64K page sizes to be specified for data, text and stack. To get the full performance benefit of 64K pages, the end user who runs the application still needs to set LDR_CNTRL such that SHMPSIZE is also set to 64K.

This idea is about adding a 'shmpsize' option to the linker which would allow to set 64K page size at link time.
If an application is then build with 64K for data/text/stack/shm sizes, it would come with the full 64K page size exploitation out-of-the-box, without the user having to worry about setting an addtl. environment variable.

Idea priority Medium
  • Guest
    Nov 22, 2022
    available in the December 2022 release of AIX 7.3 Technology Level 1
  • Guest
    Apr 26, 2022

    excellent idea and another task removed by implementing this so it works straight out of the box