The Hercules group did some testing comparing MVCL to MVC. If both source and destination had the same alignment to a double word boundary, you could move 8 bytes, then increment the 4 registers to reflect this, before being interuptable. If they aligned differently between boundaries, each 8 bytes would do this twice.
Whereas an MVC would do 256 bytes or less without interupting or touching registers, and was much faster. Of course, emulation is much different from hardware, ie, updating all 4 registers at once. On Wed, May 16, 2012 at 2:41 PM, Bernd Oppolzer <[email protected]> wrote: > First, I would like to thank you for starting this thread. > > I posted it to the performance people of my customer, and they told me, that > they just found a similar problem with EP PL/1 3.9, that is: the PLIMOVE > calls > don't generate MVCLs any more, as in previous releases, but series of MVCs > and loops. Even when the length of PLIMOVE is - for example - 8000 bytes. > They discovered it, because one of the PLIMOVE locations showed up in a > Strobe report. > > I asked them to test using a ASSEMBLER program, if the MVC loop is faster, > but they told me, that even with lengths around 500 or 600, the MVCL > solution is faster > - this is on a z196. I have still to confirm this. > > If this turns out to be true, this sounds like a bug, and we will try to > convince IBM to go back to > the previous solution. If we compile our modules during normal service using > EP PL/1 3.9, > our system will get slower and slower, because PLIMOVE is widely used. > This is not acceptable. > > Because the PLIMOVEs are generated by a site-specific macro called PLICOPY, > I already thought about calling a short ASSEMBLER routine (with minimal > linkage conventions) > doing the transfer using MVCL instead of CALL PLIMOVE. The applications need > not > to be changed, because the PLICOPY syntax stays the same. Maybe this could > still be > faster than doing the MVC loop. > > Kind regards > > Bernd -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
