Computers:Microprocessor
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Introduction
The CPU is generally the part of the computer that most people will focus on first. It is the component that drives everything else in the computer and what will handle the number crunching necessary to process the images passing through it.
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Impact on Performance
As the processor is central to all tasks performed by the computer, it is a major factor in the overall performance of the system. The speed of the processor directly dictates the rate at which major tasks such as RAW conversion and sharpening can be completed.
With that said, however, it is important to note that the processor is heavilly dependant on the rest of the system in order to keep it working. Many other components can act as bottlenecks and when that happens the CPU will generally end up sitting idle while it waits for that data to arive.
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Characteristics
There are a number of central characteristics that should be considered when selecting a processor. The following list covers the more important factors.
- Multi-Core - Many of the newest processors contain multiple processing cores inside of a single package.
- Hyper-Threading/SMT - A technique used to allow a single processing core to appear to the OS as two individual processors. This may allow more efficient use of the processor's resources.
- Clock Speed - The clock speed is the rate at which the electronics in the processor operate. While this is an important metric, it is not the only factor in overall performance.
- Cache - A block of high-speed memory that acts as an intermediary between the processor and main memory.
- Architecture - Different processors may use very different underlying architectures so performance from platform to platform is not as simple as the other numbers may suggest.
- Front-Side Bus (Intel only) - The front-side bus is the link between the processor and northbridge. As all information used by the processor must use this bus, if it is not fast enough to keep up with those components it may form a bottleneck.
- On-Board Memory Controller (AMD only) - AMD's modern processors use a memory controller built into the processor itself. This reduces latency and ensures that memory bandwidth can't be bottlenecked by a front-side bus.
- NUMA vs. UMA - Conventional computers share a single bank of memory between all of the processors in the system (UMA). AMD's newest multiprocessor systems can provide each CPU with a dedicated bank of memory (NUMA).
- AMD64/EM64T Support - Many modern microprocessors contain AMD's 64-bit extensions to the existing x86 architecture. When combined with a 64-bit OS and software, this can offer a number of potential performance benefits.
- Execute Disable Bit (XD/NX) - A security feature that prevents code from being executed in areas of memory not marked for execution.
- Vector Units (MMX,SSE,AltiVec,etc.) - Special purpose electronics allow modern processors to handle large blocks of data in a single pass. When used properly, this can provide significant improvements to many image processing tasks. Unfortunately, as this technology often requires developers to hand optimize their code it is not taken advantage of by many software packages.
It is important to note that microprocessors are extremely complicated devices and comparing products from different families is not as simple as it may seem. These characteristics give a general idea of how each processor fares, but it is important to always look for real-world tests before making a decission.
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Processor Lines
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Current
- Desktop Processors - These processors are designed for conventional desktop computers with a single socket. Often these processors will be more than sufficient for photographic workflows.
- AMD Athlon64 X2 - AMD's line of dual-core desktop processors.
- AMD Athlon64 - AMD's line of single-core desktop processors.
- Intel Core 2 Duo/Solo - Intel's line of microprocessors based on their next generation architecture. The desktop variants of this line are also known by the codename Conroe.
- Intel Pentium D - Intel's line of Netburst-based dual-core desktop processors.
- Intel Pentium 4 - Intel's line of Netburst-based single-core desktop processors.
- PowerPC 74xx (aka G4) - Freescale's line of desktop PowerPC processors used in many Macintosh computers.
- Workstation Processors - Designed for the high-end server and workstation markets, these processors are designed to work in multiprocessor systems where utmost performance is required.
- AMD Opteron - AMD's high-end workstation/server processor line. Composed of both single and dual-core processors.
- Intel Xeon 5100-series - Previously known as Woodcrest, Intel's newest line of high-end workstation/server processors based on the Core Microarchitecture.
- Intel Xeon - Intel's line of high-end workstation/server processors. Composed of both single and dual-core processors across multiple architectures (Pentium III, Netburst and Core).
- PowerPC 970 (aka G5) - Based on their high-end Power4 microprocessors, IBM's entry-level line of workstation PowerPC processors used in many modern Macintosh computers.
- Laptop Processors - Designed for portable computers where power consumption and heat output must be minimized. Provide similar performance to the desktop processors listed above, but allow smaller and lighter laptops with extremely long battery lives.
- AMD Turion - AMD's line of low-power processors, based on the Athlon64 and Athlon64 X2 cores.
- Intel Core 2 Duo/Solo - Intel's line of microprocessors based on their next generation architecture. The mobile variants of this line are also known by the codename Merom.
- Intel Core Duo/Solo - Intel's new line of low-power dual and single-core processors, often used in laptops branded as Centrino Duo.
- Intel Pentium M - Intel's older lines of low-power single-core processors, often used in laptops branded as Centrino.
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Upcoming
- Intel
- Core 2 Duo (July 27th, 2006) - Previously known as Conroe and Merom, these are the desktop and laptop implementations of Intel's next generation architecture.
- Kentsfield (2006 Q4) - Quad core successor to the upcomming Conroe XE core. Aimed squarely at the high-end gaming market, this will be Intel's top-of-the-line desktop microprocessor.
- Clovertown (2006 Q4) - Quad core version of the Kentsfield core designed for use in dual socket motherboards (providing a total of eight cores). Successor to the Woodcrest processor line.
- AMD
- K8L (2007 Q1/Q2) - Major revision of the Athlon64/Opteron architecture that will bring a number of improvements to the table (including native quad-core support).
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