I'm not really an assembler programmer, but I've known this one since my earliest days. I'm sure it was in the 370 Pop I used in my one and only assembler programming class in 1979. Good class, I have a job today because I took that class, did an internship the next semester and here I am today :)
> -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] On > Behalf Of Farley, Peter x23353 > Sent: Thursday, April 23, 2009 6:58 AM > To: [email protected] > Subject: Effective pipeline programming [was:RE: METAL C: CodeGen > defeciency?] > Obviously a thorough reading of the z/Arch PoOP will give an experienced > assembler programmer a few "don't do this, it flushes the pipeline" > cautions, like the following that I recently ran across while > researching something else entirely: > > In the notes under the Branch on Condition instruction in Chapter 7: > > "4. Execution of BCR 15,0 (that is, an instruction > with a value of 07F0 hex) may result in significant > performance degradation. To ensure optimum > performance, the program should avoid use of > BCR 15,0 except in cases when the serialization > or checkpoint-synchronization function is actually > required." > > But let's face it -- how many of us have the time to be "thorough" about > reading the PoOP? > ---------------------------------------------------------------------- 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
