Re: CallP Versus Program 'CALL'

On 2/11/2013 4:34 PM, Ken Sims wrote:

Hi Buck -

On Mon, 11 Feb 2013 14:53:06 -0500, Buck Calabro wrote:

On 2/11/2013 2:38 PM, Vernon Hamberg wrote:

I didn't see a test for a CALLP of an EXTPGM vs CALLP of EXTPROC.

As you know, CALLP is not "call procedure" - it is "call prototyped" and
can either be to a program or a procedure.

I'd expect CALLP - EXTPGM to perform about the same as a regular CALL.
But I've not tried it.

<snip>

I figured that I'd post performance numbers since the OP asked about
relative performance. I missed which relatives he was looking to
compare :-)

CALLP of an external program is just another form of CALL.

CALLP of a procedure is just another form of CALLB.

So really you were comparing CALL and CALLB.

Seems right to me.

I was conflicted posting these numbers because empirical evidence is
really only a snapshot of the current hardware/software combination. It
is possible, however unlikely, that the hardware or software of the
future could result is a different outcome. Without a manual reference
stating that this is intended to work just this way, IBM is actually
free to change the way it all works. Which is fine by me considering
all the cool new toys I've been able to play with recently.

The downside is that someone will read these numbers, make up some shop
standard for the ages and in 2030 will be wondering why his 'guaranteed
performance' isn't working out. Sort of like the advice we all heard
many years ago when we were told that too many logical files killed
performance. Or that journalling killed performance. Or that MULT was
faster than DIV.

I think the only real takeaways here are that sub-procedure calls are
quite fast compared to program calls, and that it takes a fair amount of
time to create a new activation group. The system is pretty much
behaving the way we think it ought.
--buck