Expand VFA Waitlist for DASD IO & Other types

TPFUG_Req_Number: S99011
Contact Originator Id: John Kucsera
Abstract: The VFA Waitlist whould be expanded to include DASD IO and if possible, any other looping type IO for tapes, MPIF, SNA, etc. that the TPF USER might want to remove from the CPU LOOP and delay the application slightly
Description: DASD (not unlike VFA) IO can dominate the CPU loop due today's large (and larger) Cache sizes and the increased usage of DASD / CACHE FAST WRITE.

The VFA Waitlist was installed to handle looping tasks for VFA, now its time for DASD and perhaps additional loop dominating activity to likewise use the VFA Waitlist or a like list.

The VFA Waitlist should be expanded to include DASD IO (, and if possible any other looping type IO for tapes, MPIF, SNA, etc, the TPF USER might want to remove from the CPU LOOP and) delay the application slightly.

The VFA WAITLIST COUNTS (RENAMED – perhaps the "CPU WAITLIST COUNTS") should be a SIPGEN OPTION – that allows the TPF user the option of how many CPU loop passes before the ECB can be considered a "Utility" and waitlisted.

Detection Levels

ECB TYPE 1st time Each additional
VFA ECB 40 loops than wait Each 20 loops than wait
DASD ECB 20 loops than wait Each 10 loops
TAPE ECB 10 Loops 5 loops
Other 5 Loops 5 loops At "SYSTEM GEN" time, the TPF user decides what applications, at what interval 1st time, 2nd, etc , and how long.
Critical Success Factors: SIPGEN OPTION: THE CUSTOMER SELECTS WAITLIST OPTIONS
Solution Considerations: DASD / TAPE / OTHER IO CAN DOMINATE THE CPU LOOP – causes lower loops to backup – and perhaps deplete storage.