PowerPC and POWER2: Technical Aspects of the New IBM RS/6000

• POWER2: Next Generation of the RS/6000 Family
• POWER2 CPU-Intensive Workload Performance
• POWER2 Performance on Engineering/Scientific Applications
• POWER2 Commercial Workload Performance
• POWER2 Floating-Point Unit: Architecture and Implementation
• POWER2 Fixed-Point, Data Cache, and Storage Control Units
• POWER2 Instruction Cache Unit
• POWER2 Performance Monitor
• Algorithm and Architecture Aspects of Producing ESSL BLAS on POWER2
• PowerPC Architecture: A High-Performance Architecture with a History
• PowerPC 601 Microprocessor
• PowerPC 603 Microprocessor
• POWER, POWER2, and PowerPC Migration and Compatibility
• Using the XL Compiler Options to Improve Application Performance

Foreword
In February of 1990, IBM introduced the RS/6000 product line. The announcement raised the performance bar beyond our customers' and competitors' expectations. Along with the initial announcement, IBM provided a collection of related papers. This popular IBM RS/6000 Technology book became a widely accepted reference guide for the RS/6000 family.

Over the years, the product line was enhanced with faster processor clocks, larger caches, more memory, new AIX and compiler releases, and new levels of integration and function of adapters.

Over time, even the performance metrics used to compare the systems became obsolete. At the time of the first announcement, the Dhrystone benchmark was popular. Gradually, more robust benchmarks, such as the SPECfp89 and SPECint89 suites, became the prominent industry standard comparisons. Even those suites have recently been replaced by the SPEC CFP92 and CINT92 suites.

In the fall of 1993, IBM announced new POWER2-based and PowerPC-based systems, new graphics capabilities, and new software capabilities. In an effort to update the material to cover the new offerings, as well as to incorporate the changes over the years, this second technology book has been created.

In the tradition of the original volume, this book contains the works of many RISC System/6000 developers. Its primary purpose is to provide background and insight into the RS/6000 family. It is intended to convey technical information about RISC System/6000 products that is not otherwise generally available.

We thank Phil Hester, Mary Ann Messina, and others for sharing their thoughts that helped guide the selection of topics. We are grateful to the authors, who in addition to bringing exceptional products to market, found time in their schedules to provide the reader with their views of the products.

Article reviewers were selected both to provide a technical review and to improve overall readability. We thank Kate Stewart, Maurice Franklin, Jack Kemp, Marc Pawliger, Kaivalya Dixit, and Michael Amerson for providing many useful comments that have greatly improved this book.

In some cases, papers submitted to the IBM Journal of Research and Development covered areas that are key to this book. We thank the Journal editors for granting us permission to reprint some portions of the submissions covering POWER2. We also thank IEEE for granting us permission to reprint the PowerPC 601 article.

We thank Phil Hester, Chuck Michalik, and Rich Anderson for supporting this effort and for providing the technical community a forum in which to present their material.

Steve White and John Reysa

Preface
The 1990 announcement of the RS/6000 family and the AIX operating system moved IBM to the forefront of the workstation industry. During the following three years, IBM enhanced the product line with both single-and multiple-chip implementations. Over this period, SPEC performance nearly quadrupled, transaction performance improved by a factor of almost five, the maximum memory capacity quadrupled, and the maximum DASD capacity grew by an order of magnitude. Several improvements in high-speed interconnect and graphics also occurred. The robust product line addressed the cost-driven requirements of the entry workstation market, the transaction and server requirements of the commercial market, and the compute intensive requirements of the technical market.

IBM's wide-ranging announcement in the Fall of 1993 represents the most significant product introduction since the original RS/6000. The new POWER2 processor nearly doubled the performance of the high-end models. The PowerPC 601 processor was introduced in the Model 250, the first system in the industry to use the PowerPC Architecture created by the strategic IBM/Motorola/Apple alliance. The Model 250 made a big impact in the graphics industry, providing industry-leading 2-D performance. Across the board, these systems achieved industry-leading performance and price/performance on virtually every industry standard benchmark.

The hardware announcements complemented an equally impressive array of enhancements to software including new compilers, AIX 3.2.5, emulation software, and soft graphics. The new compilers included additional transformations and optimizations, supported the new hardware offerings, and added C++ and full Fortran 90 support. AIX system management enhancements included visual and distributed SMIT as well as improved install time. Emulation software will allow a single open platform to concurrently run AIX, PC, and Macintosh applications with very good performance. The new 3-D rendering software packages, along with the performance levels of the recent hardware offerings, have provided an alternative to costly 3-D graphics adapters. This graphics software also has the desirable characteristic of being able to adapt to and benefit from future processor improvements.

These hardware and software offerings, some of which are described in this book, expand the RS/6000 line and result from a team effort requiring many dedicated and talented individuals from around the world. Their expertise and skill in a wide range of disciplines were key to achieving this significant step toward our "Palmtops to TeraFLOPS" strategy. I want to thank all those involved in continuing the success of the RISC System/6000 line.

Bill Filip
IBM Vice President and President,
RS/6000 Division

Trademarks
The following trademarks apply to this set of papers. They are listed in alphabetical order, not in the order in which they appear in the papers.

• AIX is a registered trademark of International Business Machines Corporation.
• AIX/6000 and AIXwindows are trademarks of International Business Machines Corporation.
• Alpha is a trademark of Digital Equipment Corporation.
• ANSI is a trademark of American National Standards Institute.
• ANSYS is a registered trademark of Swanson Analysis Systems, Inc.
• Apollo is a trademark of Apollo Computer, Inc.
• Apple is a registered trademark of Apple Computer Corporation.
• AXP is a trademark of Digital Equipment Corporation.
• C Set ++ is trademark of International Business Machines Corporation.
• Cray is a registered trademark of Cray Research, Inc.
• DB2/6000 is a trademark of International Business Machines Corporation.
• DEC and DECstation are registered trademarks of Digital Equipment Corporation.
• Ethernet is a trademark of XEROX Corporation.
• graPHIGS is a trademark of International Business Machines Corporation.
• Groupe Bull is a trademark of Groupe Bull.
• HP is a registered trademark of Hewlett-Packard Company.
• IBM is a registered trademark of International Business Machines Corporation.
• IBM Shared Memory System is a trademark of International Business Machines Corporation.
• IEEE is a registered trademark of the Institute of Electrical and Electronics Engineers.
• InfoExplorer is a trademark of International Business Machines Corporation.
• Intel is a registered trademark of Intel Corporation.
• Internet is a registered trademark of Internet, Inc.
• IRIS Graphics Library is a trademark of Silicon Graphics, Inc.
• KAP is a trademark of Kuck and Associates, Inc.
• Kaleida is a trademark of Kaleida.
• Macintosh is a registered trademark of Apple Computer Corporation.
• MECHANICA is a registered trademark of Rasna Corporation.
• Micro Channel is a registered trademark of International Business Machines Corporation.
• Microsoft is a registered trademark of Microsoft Corporation.
• MIPS is a registered trademark of MIPS Computer Systems, Inc.
• MIT is a registered trademark of Massachusetts Institute of Technology.
• Motorola and Motorola 88110 are trademarks of Motorola, Inc.
• MSC is a registered trademark of The MacNeal-Schwen dler Corporation.
• NASTRAN is a registered trademark of the National Aeronautics and Space Administration.
• Network File System is a trademark and NFS is a registered trademark of Sun Microsystems, Inc.
• OpenGL is a trademark of Silicon Graphics, Inc.
• OSF, Motif, and OSF/Motif are registered trademarks of Open Software Foundation.
• Perfect Benchmarks is a trademark of the Center for Supercomputing Research and Development, Univ. of Ill. at Urbana-Champaign.
• POWER/4, POWER Architecture, POWER2, POWER, PowerOpen, POWERstation, POWERserver, POWER GXT100, POWER GTX150, RGB 530, PowerPC, PowerPC Architecture, PowerPC 601, PowerPC 603, PowerPC 604, PowerPC 620, Presentation Manager, and RS/6000 are trademarks of International Business Machines Corporation.
• PS/2 is a registered trademark of International Business Machines Corporation.
• Silicon Graphics is a trademark of Silicon Graphics, Inc.
• SPEC, SPECmark, SPECfp92, and SPECint92 are trademarks of Standard Performance Evaluation Corporation.
• Spectrum is a trademark of the CENTRIC Engineering Systems, Inc.
• SP1 is a trademark of International Business Machines Corporation.
• SuperSPARC is a trademark of SPARC International, Inc. used under license by Texas Instruments, Inc.
• Taligent is a trademark of Taligent.
• TPC Benchmark, TPC-A, TPC-B, and TPC-C are trademarks of the Transaction Processing Performance Council.
• UNIX is a registered trademark of UNIX Systems Laboratories.
• VAST is a trademark of Pacific-Sierra Research Corporation.
• X Window System is a registered trademark of Massachusetts Institute of Technology.