I'm no assembler expert, but how about L R15,COUNTER AFI R15,1 ST R15,COUNTER
> Date: Fri, 22 Jan 2016 14:14:49 -0500 > From: [email protected] > Subject: Re: Is there a source for detailed, instruction-level performance > info? > To: [email protected] > > In article <[email protected]> Skip wrote: > > > As a newbie, I got curious about the relative speed of these strategies: > > > > 1. L R15, COUNTER > > 2. A R15,=F(+1) > > 3. ST R15, COUNTER > > > > 1. L R15, COUNTER > > 2. LA R15,1(,R15) > > 3. ST R15, COUNTER > > > > I asked my manager, who encouraged me to delve into the manual Shmuel cites. > > I decided that LA was faster because there was no storage access. The > > program ran like a banshee. It ran so fast that it was used to benchmark new > > hardware. Really! > > > > It wasn't till later that I pondered a basic flaw. As written, the program > > could not handle a counter greater than 16M because it ran in 24 bit mode. > > This was before XA. At the time I wrote it, the data base was comfortably > > within that limit, but over time, long after I had moved on, I (still) > > wonder if the application survived and if any counter ever hit the limit. > > Moral: whether or not size matters, speed is certainly not a simple metric. > > L R15,COUNTER > BCTR R15,0 > ST R15,COUNTER > > gives a 2^31 limit, 2^32 if some care is taken when printing the totals, at > speed comparable to LA. > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
