On 5/31/2011 5:22 PM, Gibney, Dave wrote:
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.
On all the machines I tried it, with fixed length 256 byte moves versus MVCL, MVCL was faster for a total length larger than 1K (370 and 43x1) or 4K (more recent). Test were on an (otherwise) idle machine. My guess is that MVCL has less setup overhead compared to multiple MVCs?
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.
Agreed; and I make use of the updated addresses, and the padding is nice.
In answer to Mike Schwab: back in the seventies we had customers for our software using both 360 and 370 machines, and assorted systems (MFT, MVT, SVS, MVS). As much of the code as possible tested the environment and adjusted; for many cases, I used conditional assembly. One such case was an LMVC macro that either expanded an MVC loop or one MVCL.
Gerhard Postpischil Bradford, VT ---------------------------------------------------------------------- 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
