Peter, DB2 has the most comprehensive support to interact with WLM to address contention. DB2 will try to notify WLM about resource contention to extent it knows about dependencies. Based on such notifications DB2 and WLM support - Regular "enqueue promotion" and short term promotion . Both promote the holder of the lock to an elevated dispatch priority, increasing its chances to get dispatched. Search for "Sysevent ENQHOLD") - Chronic contention. Elevates the resource holder to the highest dispatch priority of any waiter. (Search for IWMCNTN).
Still there can be situations where neither DB2 (and certainly no one else) knows the dependencies. For such cases the blocked workload support provides the capability that *any* address space that has been blocked -not dispatched- for a given time will be granted one time slice. That's a very small amount of processor time and it is handed out *independently* of any contention. Yet it is proven to be a very effective way to address DB2 latch contention. (Only latches typically gate such a short path that the contention can be resolved through one or a few of such "trickles".) See the ENV and BLWLINTHD IEAOPTxx parameter (BLWLTRPCT is almost never the limiting fact). Searching for OA44526 will give you a good list of recommendations. DB2 and GRS locks are unrelated (except for allocation related ones). Horst Sinram - STSM, IBM z/OS Workload and Capacity Management ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
