Cell Broadband Engine Architecture Bardia Mahjour ENCM 515 March 2007 Bardia Mahjour ENCM 515 March 2007

Agenda  Introduction  History  Applications  Architecture  Features  Some Statistics  Programming Model  CBEA as DSP  Comparison with TigerSHARC  Conclusion  Introduction  History  Applications  Architecture  Features  Some Statistics  Programming Model  CBEA as DSP  Comparison with TigerSHARC  Conclusion

Introduction  Single Chip Multi-processor  9 processors built into a single die Needs that arose in areas such as:  Cryptography  Graphics transformations and lighting  Physics  Fast-Fourier Transforms (FFT)  Matrix operations  Scientifically compute-intensive tasks Goals:  power-efficient  cost-effective  high-performance processing  wide range of applications including game consoles. IBM XL Family of compilers (XL C/C++)  Single Chip Multi-processor  9 processors built into a single die Needs that arose in areas such as:  Cryptography  Graphics transformations and lighting  Physics  Fast-Fourier Transforms (FFT)  Matrix operations  Scientifically compute-intensive tasks Goals:  power-efficient  cost-effective  high-performance processing  wide range of applications including game consoles. IBM XL Family of compilers (XL C/C++) Cell die photo courtesy of Thomas Way, IBM Burlington

History  A joint venture by Sony, Toshiba, and IBM (STI)  Official Design phase started in March of 2001  Three giant companies spent 4 years and US$400M to design and develop Cell  First Commercial Use in Sony’s PlayStation 3 in November  A joint venture by Sony, Toshiba, and IBM (STI)  Official Design phase started in March of 2001  Three giant companies spent 4 years and US$400M to design and develop Cell  First Commercial Use in Sony’s PlayStation 3 in November 2006.

Applications  Console Video Games  PlayStation 3  Home Cinema  Toshiba ’ s HDTV  Embedded Applications  Medical Imaging, aerospace, telecommunication, defense, etc.  Mercury Computer Systems, Inc.  Super Computing  Roadrunner  Blade Servers  Console Video Games  PlayStation 3  Home Cinema  Toshiba ’ s HDTV  Embedded Applications  Medical Imaging, aerospace, telecommunication, defense, etc.  Mercury Computer Systems, Inc.  Super Computing  Roadrunner  Blade Servers

Architecture  PowerPC Processor Element (PPE) - 64-bit PowerPC RISC core (can run OS)  Synergistic Processor Elements (SPEs) - Each element is a DSP processor. CBEA has 8 of them!  Element Interconnect Bus (EIB)  Memory Interface Controller (MIC)  Cell Broadband Engine Interface (BEI)  PowerPC Processor Element (PPE) - 64-bit PowerPC RISC core (can run OS)  Synergistic Processor Elements (SPEs) - Each element is a DSP processor. CBEA has 8 of them!  Element Interconnect Bus (EIB)  Memory Interface Controller (MIC)  Cell Broadband Engine Interface (BEI)

Features PPE has a pipeline 10 levels deep Each SPE has:  a 128x128 register file  a floating-point unit  two fixed-point units  VMX vector arithmetic unit  Local Store  DMA controller PPE has a pipeline 10 levels deep Each SPE has:  a 128x128 register file  a floating-point unit  two fixed-point units  VMX vector arithmetic unit  Local Store  DMA controller

Some Statistics  Observed clock speed: > 4 GHz  Peak performance (single precision): > 256 Gflops  Peak performance (double precision): >26 GFlops  Local storage size per SPU: 256KB  Area: 221 mm ²  Technology 90nm SOI  Total number of transistors: 234M  Observed clock speed: > 4 GHz  Peak performance (single precision): > 256 Gflops  Peak performance (double precision): >26 GFlops  Local storage size per SPU: 256KB  Area: 221 mm ²  Technology 90nm SOI  Total number of transistors: 234M

Programming Model  Function Offload Model  Device Extension Model  Computational Acceleration Model  Streaming Models  Shared-memory Multi-processor Model  Asymmetric Thread Runtime Model  User-Mode Thread Model  SPE Overlay  Function Offload Model  Device Extension Model  Computational Acceleration Model  Streaming Models  Shared-memory Multi-processor Model  Asymmetric Thread Runtime Model  User-Mode Thread Model  SPE Overlay

Function Offload Model Remote Procedure Call (RPC)

/* file hello.idl */ interface greeting{[sync] idl_id_t hello ([in] int nbytes, [in, size_is(nbytes)] char message[]);} /* file hello.c */ #include int main( ){ char* str = “Hi, from the Cell!”; hello( strlen(str), str); } /* file spu_hello.c */ #include idl_id_t hello( int nbytes, char msg[]) { printf(“SPE: %s\n”, ms); return 0; } /* file hello.idl */ interface greeting{[sync] idl_id_t hello ([in] int nbytes, [in, size_is(nbytes)] char message[]);} /* file hello.c */ #include int main( ){ char* str = “Hi, from the Cell!”; hello( strlen(str), str); } /* file spu_hello.c */ #include idl_id_t hello( int nbytes, char msg[]) { printf(“SPE: %s\n”, ms); return 0; } Function Offload Model

Thread Runtime Model speid_t spe_create_thread( spe_gid_t gid, spe_program_handle_t *spe_program_handle,void *argp, void *envp, unsigned long *mask, int flags ); Example PPE Code: #include #define NUM_SPES 8 extern spe_program_handle_t spe_code; int main( ) { for (i = 0; i < NUM_SPES; i++) spe_ids[i] = spe_create_thread(gid,&spe_code, NULL, NULL, -1, 0); return 0; } speid_t spe_create_thread( spe_gid_t gid, spe_program_handle_t *spe_program_handle,void *argp, void *envp, unsigned long *mask, int flags ); Example PPE Code: #include #define NUM_SPES 8 extern spe_program_handle_t spe_code; int main( ) { for (i = 0; i < NUM_SPES; i++) spe_ids[i] = spe_create_thread(gid,&spe_code, NULL, NULL, -1, 0); return 0; }

CBEA as DSP Strictly speaking : Cell is a microprocessor Designed to bridge the gap between conventional and special-purpose processors Handles heavy digital signal processing workloads ( 3D graphics, 48 MPEG-2 Channels, etc. ) Meets most of the ideal DSP processor requirements Strictly speaking : Cell is a microprocessor Designed to bridge the gap between conventional and special-purpose processors Handles heavy digital signal processing workloads ( 3D graphics, 48 MPEG-2 Channels, etc. ) Meets most of the ideal DSP processor requirements

Comparison with TigerSHARC  Size requirement  Power consumption and heat generation  Supports floating-point ops in hardware  Bandwidth and data-width  Avoids resource dependencies  Scalability  Ease of programming  Size requirement  Power consumption and heat generation  Supports floating-point ops in hardware  Bandwidth and data-width  Avoids resource dependencies  Scalability  Ease of programming

Conclusion Cell Broadband Engine Architecture is an extremely powerful, scalable and fast processor. It is not purely a digital signal processor, however, the wide range of applications it is suited for includes DSP. Furthermore, many of the requirements of DSP applications were the rationale behind CBEA ’ s design and architectural decisions.

References [1] IBM Research, The Cell Architecture, Innovation Matters. Available at Accessed Feb 19 th, 2007 [2] IBM Systems and Technology Group, Cell Broadband Engine Programming Tutorial Version 2.0, December 15, 2006 [3] Wikipedia, Cell Microprocessor Implementations. Available at - endnote_sti32nmhttp://en.wikipedia.org/wiki/Cell_microprocessor_implementations - endnote_sti32nm Accessed Feb 20 th, 2007 [4] Signalogic , DSP Applications. Available at Accessed Feb 21 st, 2007 [5] Wikipedia, Cell Microprocessor. Available at Accessed Feb 22 nd, 2007 [6] IBM Journal of Research and Development, Introduction to the Cell multiprocessor (September 7, 2005) Available at [7] Smith, M. R. (1992). How RISCy is DSP? Micro, IEEE, Volume 12, Issue 6, [8] Analog Devices Inc. One Technology Way, ADSP-TS201 TigerSHARC Processor Programming Reference, Version 1.1, April 2005 [1] IBM Research, The Cell Architecture, Innovation Matters. Available at Accessed Feb 19 th, 2007 [2] IBM Systems and Technology Group, Cell Broadband Engine Programming Tutorial Version 2.0, December 15, 2006 [3] Wikipedia, Cell Microprocessor Implementations. Available at - endnote_sti32nmhttp://en.wikipedia.org/wiki/Cell_microprocessor_implementations - endnote_sti32nm Accessed Feb 20 th, 2007 [4] Signalogic , DSP Applications. Available at Accessed Feb 21 st, 2007 [5] Wikipedia, Cell Microprocessor. Available at Accessed Feb 22 nd, 2007 [6] IBM Journal of Research and Development, Introduction to the Cell multiprocessor (September 7, 2005) Available at [7] Smith, M. R. (1992). How RISCy is DSP? Micro, IEEE, Volume 12, Issue 6, [8] Analog Devices Inc. One Technology Way, ADSP-TS201 TigerSHARC Processor Programming Reference, Version 1.1, April 2005