On Mon, 3 Dec 2007 16:33:29 -0600, Patrick O'Keefe <[EMAIL PROTECTED]> wrote: > >I understand that the CPACF instructions are just that - single >instructions. But so are AR, MVCL, and CFC - quite a range. >(I'm guessing that CFC takes a long time to execute. It's >description takes a long time to read!). I'm guessing that the >CPACF instructions are implemented in millicode and may not >execute quite as fast, and represent quite as light a load on the >CP, as AR (for example). > >One of the people here suggested that enabling the feature did >nothing more than enabled instruction decode - that the cycles >burned were about the same - hardware or software. I would like >to refute that if the appropriate doc exists. > >Pat O'Keefe
when we were developing our tape encryption product for the z/VM environment, we did some timing and performance tests between the software implementations of popular encryption algorithms (DES, TDES, AES) and the hardware implementations IBM provides (CPACF) on the z9 boxes. The hardware implementation were anywhere between 100x and 255x times faster that the software ones on processing significant amounts of data (over a megabyte, say). The software routines were hand coded in S/390 assembler for maximum performance, as well. Of course, the hardware instructions can execute for significant amounts of time as well; these instructions can return control with condition code 3 (I think) set, meaning that the instruction has not finished processing all of the data it needs to and should be reissued. DJ V/Soft z/VM and mainframe Linux expertise, training, consulting, and software development www.vsoft-software.com ---------------------------------------------------------------------- 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
