HP-UX HB v13.00 Ch-21 - Itanium

HP-UX Handbook – Rev 13.00 Page 29 (of 35)
Chapter 21 Itanium Architecture (IA)
October 29, 2013
Performance
Because an emulator can never be as performant as native code Aries should be used where
performance is not critical or where it is not possible to create a native IPF family binary.
Depending on the type of application you will see more or less impact on performance compared
to PA-RISC. Here’s an extract of the aries man page:
Aries performance can be characterized by following points:
1) For PA-RISC applications that have an average mix of system intensive, I/O intensive, and
memory intensive operations, Aries performance on an Itanium2-based machine running at
1500 MHz is of the order of or better than a PA8700-based machine. For such PA-RISC
applications, Aries performance may be closer to an Itanium2-based machine's native
performance.
2) For PA-RISC applications that have integer intensive operations, Aries performance on an
Itanium2-based machine running at 1500 MHz is about 70-80% of a PA8700-based machine
and is 10-15% better than PA8600-based machine. For such PA-RISC applications, Aries
performance is 35-40% of Itanium2-based machine's native performance.
3) For PA-RISC applications that have floating point intensive operations, Aries performance
on an Itanium2-based machine running at 1500 MHz is about 50% of a PA8700-based
machine and about 70% of PA8600 based machine. For such PA-RISC applications, Aries
performance is only 10-15% of an Itanium2-based machine's native performance.
4) For PA-RISC virtual machines like JVM (Java Virtual Machine), Aries performance is
slower of the order of 15-20 times compared to an Itanium2-based machine's native
performance. Such applications are not good candidates for execution in emulation mode
under Aries.
5) Aries performance for multi-threaded PA-RISC applications is poorer than the non-
threaded counterpart of the same application. This is because Aries implements internal
mutex locks to protect Aries private data structures. Aries threads need to reach a safe point
before they can be suspended. This condition adds to the performance penalty as the calling
thread will have to wait until the target thread reaches the safe zone before it can be
suspended. This is required, as before suspending a thread, Aries has to make sure that PA-
RISC application's emulated register context is consistent in registers and memory.
6) PA-RISC applications which make use of performance libraries like HP mlib are not good
candidates to run under Aries. Performance library (for example, HP mlib) kernels are hand-
coded in assembly and are tuned to the cache behavior and instruction resources as to achieve
closer to theoretical machine peak rate. It is not possible for a software emulator like Aries
to emulate this detailed behavior of the application for maximum hardware resource