Jim, I wholeheartedly agree with you, Both the DFSORT and the SYNCSORT guys have done a great job of exploiting DIM techniques to make the most of what is generally an IO bound process. With both sort products I think it is fair to say that they will only use the SORTWK when Hiperspace and Dataspace are less than the sort requires, or when memory is artificially capped.
Problem (it is a small problem) is we have a plethora of small SORTWK (SASSWK, etc) files allocated through JCL, or Dynamically, that are good candidates for VIO. However, in performance the rules of thumb often become "laws of thumb", and rote learning of performance recommendations like this have a tendency to disguise the original reason for the rule. Net result is that nine out of ten ACS routines are built with SORTWK excluded from VIO without anyone actually knowing why. In this case, even a vendor is blindly recommending excluding SYNCSORT SORTWK files from VIO with what I believe to be an outdated premise. Why? Ron > > I would expect VIO to ESTOR (ESA/390) or real storage (z/Architecture) > would be considerably faster than doing real I/O. But if you are going > to use a given amount of ESTOR or real storage for sorting, it is probably > more efficient (in terms of CPU cycles) to let the sort product access > the storage directly through a Hiperspace (for ESTOR in ESA/390) or > 64-bit virtual or data space (for real storage in z/Architecture), thus > avoiding the CPU cycles to build a channel program, only to have EXCP > expend > more cycles to interpret the channel program. > > VIO to ESTOR or real storage remains a good I/O avoidance method for > programs which are not designed to exploit real/expanded storage directly, > and for passing data to a subsequent job step. > > Jim Mulder z/OS System Test IBM Corp. Poughkeepsie, NY > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO > Search the archives at http://bama.ua.edu/archives/ibm-main.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
