Gary_Cherlet

Release 18 ADS User Built-in-Functions possible performance issue

Discussion created by Gary_Cherlet on Apr 1, 2013
Latest reply on Apr 3, 2013 by Eddy_G
While investigating a recent performance issue, after a Release 18 upgrade, at a "sister site" - we realised that their User built-in-functions (BiFs), which had been linked into ADSOMAIN for many years, were no longer being called with "internal calls" - rather they were being called through #LOAD! On their smaller machine this caused significant CPU issues which showed up rather quickly, particularly since it not only impacted Production IDMS but also affected their Development IDMS and TSO.

When we checked on our Production system we saw that our User BiFs were also getting "Times Called" count greater than 0 (zero) - so clearly we were no longer getting the CPU savings that you get when internal CALLs are used by linking the BiFs into ADSOMAIN. While we had seen a CPU increase with Release 18 - it was not so dramatic as at the 2nd site (also we have a separate LPAR for development) - so we had not bothered to look any further. In any event there is a reason - here is a note we got from out out-sourcer after we pointed out the problem:
[color=#0000a2]I went back to review R18 documentation on ADSOMAIN. It appears that we no longer link edit USER BIF with ADSOMAIN as we do in the past. Instead we can Optionally create an ADSOVCON module using the #BIFVCON macro to identify your user-written BIF modules to be linked together[color]
I have attached a document that provides further details - I hope that this will help other users from bumping into this problem during their upgrades. BTW - I have seen performance improvements (i.e. CPU reduction) in CA-ADS shops where BiFs are heavily used of up to 20-25%. This is of course dependent on a great many variables - but it does indicate the significant difference between "internal calls" and #LOAD calls - our User BiFs get somewhere between 8M-10M "times called" counts per day when not linked in to ADSOMAIN.

Cheers - GaryC

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