Accelerator Manual (G06.24+, H06.03+)

Introduction
Accelerator Manual—527303-002
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When to Use the Accelerator
The Accelerator can process bound, executable object programs generated by B40
and later releases of the C, COBOL85, FORTRAN, Pascal, and TAL compilers. The
Accelerator can process executable object programs that run in either the Guardian or
Open System Services (OSS) environment. (You cannot accelerate object programs
generated by the COBOL 74 compiler.)
When to Use the Accelerator
Use these guidelines to determine whether to accelerate your TNS program:
•
If CPU performance is not an issue (for example, the program is I/O-bound), you
gain little measurable performance improvement by accelerating the program.
Where CPU performance is an issue, there is great advantage to accelerating: the
program usually runs several times faster when accelerated.
•
If your program consists mainly of calls to system code, you do not gain much
performance improvement by accelerating the program itself. HP system code has
been native-compiled on D-series systems and accelerated on C-series and D-
series systems. Many OLTP applications, for example, spend 90 percent or more
of their time in system code, so there is little to be gained by accelerating those
applications.
•
If your program runs in the Open System Services (OSS) environment, you gain
significant performance by accelerating the program. HP strongly recommends that
you accelerate programs running in the OSS environment.
You can use the Measure system performance-analysis tool to determine which
programs can be significantly improved by using the Accelerator. For example, use
Measure to collect data on the PROCESSH entity. The PROCESSH entity type collects
data on the amount of time a program executes in the four code spaces: user code,
user library, system code, and system library.
When measuring application performance, select a measurement window that
coincides with some representative portion of the system workload, usually the
system’s peak time. For further verification, take and compare multiple measurements
to create a level of confidence with the data collected.
After you accelerate your application, you can use the PROCESSH entity to determine
the amount of time your application spends executing TNS code, accelerated code,
and native-compiled code.
In summary, accelerate your program if it spends most of its time in user code
(including user libraries) and if CPU performance is important. Contact your HP analyst
for additional help in determining which applications benefit the most from using the
Accelerator.