topic performance and +DAportable in Operating System - HP-UX

performance and +DAportable

Ian Lochray — Fri, 29 Jun 2001 10:26:34 GMT

I have a large application that is written in C and COBOL. I want to build it on a PA RISC 2.0 chip but I want my customers who still have PA 1 chips to be able to run it so I compile with the +DAportable option. I want to know if there are any performance implications of this when compared with buildingthe application on a PA 1 chip.

Re: performance and +DAportable

Rainer von Bongartz — Fri, 29 Jun 2001 10:42:47 GMT

I have done this kind of thing and didn't notice nor measure any performance implications.

Re: performance and +DAportable

Herve BRANGIER — Fri, 29 Jun 2001 11:00:41 GMT

Hi

Reading information it seems that performances
are falling... but we do that without measurables
differences....

Regards

Herv?

Re: performance and +DAportable

A. Clay Stephenson — Fri, 29 Jun 2001 13:54:21 GMT

Hi Ian,

I doubt that you will see any degradation in any COBOL application since these tend to be I/O intensive rather that computationally intensive. The only cases in which I have observed any measurable differences in performance involved analysis programs in C involving very large arrays and very complex math. In that case, the performance hit was about 4% (in that particular section of code) but in the vast majority of cases, you will find that the hit is not measurable.

In any event, the proper course is to compile and link using both options and measure but I think all will be well if you choose portable.

Regards, Clay

Re: performance and +DAportable

Mike Stroyan — Fri, 29 Jun 2001 17:12:31 GMT

One thing you can do to compromise is to use +DAportable and +DS2.0 to make the compiler use PA1.1 features but schedule instructions to run best on PA2.0 systems. The default scheduling for +DAportable can be very far from optimal for modern systems.

Re: performance and +DAportable

Andrew Cunningham — Mon, 02 Jul 2001 20:18:40 GMT

On our computationally intensive C/C++ application I found at least a 20-30% performance hit on our B1000 when running +DAportable compiled ( latest aCC, HP-UX 10.2).