Skip to Main Content
IBM Data and AI Ideas Portal for Customers


This portal is to open public enhancement requests against products and services offered by the IBM Data & AI organization. To view all of your ideas submitted to IBM, create and manage groups of Ideas, or create an idea explicitly set to be either visible by all (public) or visible only to you and IBM (private), use the IBM Unified Ideas Portal (https://ideas.ibm.com).


Shape the future of IBM!

We invite you to shape the future of IBM, including product roadmaps, by submitting ideas that matter to you the most. Here's how it works:


Search existing ideas

Start by searching and reviewing ideas and requests to enhance a product or service. Take a look at ideas others have posted, and add a comment, vote, or subscribe to updates on them if they matter to you. If you can't find what you are looking for,


Post your ideas

Post ideas and requests to enhance a product or service. Take a look at ideas others have posted and upvote them if they matter to you,

  1. Post an idea

  2. Upvote ideas that matter most to you

  3. Get feedback from the IBM team to refine your idea


Specific links you will want to bookmark for future use

Welcome to the IBM Ideas Portal (https://www.ibm.com/ideas) - Use this site to find out additional information and details about the IBM Ideas process and statuses.

IBM Unified Ideas Portal (https://ideas.ibm.com) - Use this site to view all of your ideas, create new ideas for any IBM product, or search for ideas across all of IBM.

ideasibm@us.ibm.com - Use this email to suggest enhancements to the Ideas process or request help from IBM for submitting your Ideas.

IBM Employees should enter Ideas at https://ideas.ibm.com


Status Delivered
Workspace Db2 for z/OS
Created by Guest
Created on Jul 19, 2019

Change IRLM hashing algorithm to offer a better and more efficient distribution of P-locks across LTEs

As per PMR 76883,999,866/TS002531202, when increasing DSMAX and PCLOSET/N parms to reduce TCB DBM1 CPU time owing to less open/close operations, we noticed a significant increase in IRLM CPU time, strongly correlated with higher number of currently opened datasets.  Further PMR analysis has  shown that IRLM hashing algorithm can hash so many pageset/partition P-locks into a relatively small set of LTEs, that it makes IRLM deadlock detection processing very expensive. This is because IRLM deadlock processing is having problems with very long chains of resources per hash value, which in turn causes significant CPU overhead. This is especially visible when IRLM needs to hash a large number of partitions defined on the same DBID. That is a serious scaling limitation which cannot be easily resolved. This issue has been discussed with IBM in more detail and it has been suggested that IRLM hashing algorithm may have to be redesigned.

  • Admin
    Janet Figone
    Reply
    |
    Dec 11, 2019

    We are pleased to inform you this AHA Idea has been delivered via APAR PH17336/PTF UI66284. We appreciate your input and hope you will continue to submit your Ideas for our consideration for the Db2 for z/OS product.

  • Guest
    Reply
    |
    Dec 11, 2019

    This idea is implemented by PH17336/UI66284.  UI66284 is available for order.