That was the conclusion apparently last time around:
http://groups.google.com/group/bit.listserv.ibm-main/browse_thread/thread/5f
59748279c428bc/fee5e1d477452dfb
I certainly agree with your second paragraph. It would have to be mighty
repetitive code for me to worry about this.
You could carry this to any length you wanted. If you knew you were dealing
fewer than 4096 bytes you could avoid the MVC *loop* by having a branch
table based on length/256 that took you to:
Move256to512 EQU *
MVC TO(256),FROM
B ExecuteLogic
*
Move512to758 EQU *
MVC TO(256),FROM
MVC TO+256(256),FROM+256
B ExecuteLogic
*
Move758to1024 EQU *
MVC TO(256),FROM
MVC TO+256(256),FROM+256
MVC TO+512(256),FROM+512
B ExecuteLogic
*
Etc.
Charles
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf
Of Gibney, Dave
Sent: Tuesday, May 31, 2011 2:22 PM
To: [email protected]
Subject: Re: What is the current feeling for MVC loop vs. MVCL?
As I am led to understand it, under the covers in the millicode MVCL really
is a MVC loop. So MVCL is at least slower by the cost of overhead switching
into the millicode environment.
That said, and if I was coding anything which I'm not these days, I'd likely
do the MVCL and be done with it unless I knew it was a very frequently
executed path in the code.
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