Intel Turbo Boost: Difference between revisions
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== Practical concerns == |
== Practical concerns == |
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While Turbo Boost has the potential to speed up single threaded tasks that are unable to otherwise take advantage of the additional cores, it is very rare to see the full advantage in practice. At issue is the need for two or three cores to be inactive to reach the two or one core active turbo speeds; Windows will take a single thread and run 25% of it on each of four cores instead of putting it all on one core.{{Citation needed|date=May 2011}} While, since it is a single thread, there is only one core active at a time, the other cores need time to go to sleep and allow the running core to boost up. As a result, the single-core speed is not seen and the two-core speed is rarely seen unless [[processor affinity]] has been set to a single core.<ref>[http://www.tomshardware.com/reviews/intel-core-i5,2410-4.html Intel’s Turbo Boost: Lynnfield Gets Afterburners : Intel Core i5 And Core i7: Intel’s Mainstream Magnum Opus]</ref> Technology like core parking |
While Turbo Boost has the potential to speed up single threaded tasks that are unable to otherwise take advantage of the additional cores, it is very rare to see the full advantage in practice. At issue is the need for two or three cores to be inactive to reach the two or one core active turbo speeds; Windows will take a single thread and run 25% of it on each of four cores instead of putting it all on one core.{{Citation needed|date=May 2011}} While, since it is a single thread, there is only one core active at a time, the other cores need time to go to sleep and allow the running core to boost up. As a result, the single-core speed is not seen and the two-core speed is rarely seen unless [[processor affinity]] has been set to a single core.<ref>[http://www.tomshardware.com/reviews/intel-core-i5,2410-4.html Intel’s Turbo Boost: Lynnfield Gets Afterburners : Intel Core i5 And Core i7: Intel’s Mainstream Magnum Opus]</ref> Technology like core parking<ref>[http://drdobbs.com/article/print?articleId=228800354 Core Parking in Windows Server 2008 R2 and Windows 7 | Dr. Dobb's and Intel Go Parallel Programming]</ref> will need to evolve before full benefit is seen. |
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While the above may be true for quad-core processors, the dual-core i7-2620M (2.7GHz Sandy Bridge) processor will run with both cores in Turbo Boost indefinitely in a properly designed system. |
While the above may be true for quad-core processors, the dual-core i7-2620M (2.7GHz Sandy Bridge) processor will run with both cores in Turbo Boost indefinitely in a properly designed system. |
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Revision as of 02:16, 30 August 2011
 | This article needs to be updated. (May 2010) |
Intel Turbo Boost is a technology implemented by Intel in certain versions of their Nehalem-based CPUs, including Core i5 and Core i7 that enables the processor to run above its base operating frequency via dynamic control of the CPU's "clock rate".[1] It is activated when the operating system requests the highest performance state of the processor. Processor performance states are defined by the Advanced Configuration and Power Interface (ACPI) specification, an open standard supported by all major operating systems; no additional software or drivers are required to support the technology.[1] The design concept behind Turbo Boost is commonly referred to as "dynamic overclocking".[2]
The increased clock rate is limited by the processor's power, current and thermal limits, as well as the number of active cores and the maximum frequency of the active cores.[1] When workload on the processor calls for faster performance, and the processor is below its limits, the processor's clock will increase the operating frequency in regular increments as required to meet demand. Frequency increases occur in increments of 133 MHz for Nehalem microarchitecture processors and 100 MHz for Sandy Bridge microarchitecture processors. When any of the electrical or thermal limits are reached, the operating frequency automatically decreases in decrements of 133 MHz/100 MHz until the processor is again operating within its design limits.[1]
History
![[icon]](/wiki/File:Wiki_letter_w_cropped.svg){kind=small} | This section needs expansion. You can help by adding to it. (May 2010) |
An Intel white paper of November 2008[3] discusses "Turbo Boost" technology as a new feature incorporated into Nehalem-based processors released in the same month.[4]
A similar feature called Intel Dynamic Acceleration (IDA) was available on many Core 2 based Centrino platforms.[5] This feature did not receive the marketing treatment given to Turbo Boost. Intel Dynamic Acceleration dynamically changed the core frequency as a function of the number of active cores. When the operating system instructed one of the active cores to enter C3 sleep state using the Advanced Configuration and Power Interface (ACPI), the other active core(s) dynamically accelerated to a higher frequency.
Example
(Taken from the list of Intel Core i7 microprocessors.)
For Core i7-920XM.
The normal operating frequency is 2.0 GHz. Turbo is indicated as: 2/2/8/9 in which the first number is the multiple of 133.33 MHz supported when four cores are active, the second number is the multiple for three cores, the third number is for two cores, and the fourth number is for one active core.
Subject to limits on temperature, current and power consumption, the processor can increase its clock speed (from a base frequency of 2.0 GHz) in steps of 133 MHz to:
| # of cores active | # of Turbo Steps | Max frequency | Calculation |
|---|---|---|---|
| 3 or 4 | 2 | 2.26 GHz | 2000 + 2 × 133 = 2000 + 266 ≃ 2266 |
| 2 | 8 | 3.06 GHz | 2000 + 8 × 133 = 2000 + 1066 ≃ 3067 |
| 1 | 9 | 3.20 GHz | 2000 + 9 × 133 = 2000 + 1199 ≃ 3200 |
For Core i7-2920XM.
The normal operating frequency is 2.5 GHz. Turbo is indicated as: 7/8/9/10 in which the first number is the multiple of 100 MHz supported when four cores are active, the second number is the multiple for three cores, the third number is for two cores, and the fourth number is for one active core.
Subject to limits on temperature, current and power consumption, the processor can increase its clock speed (from a base frequency of 2.5 GHz)in steps of 100 MHz to:
| # of cores active | # of Turbo Steps | Max frequency | Calculation |
|---|---|---|---|
| 4 | 7 | 3.20 GHz | 2500 + 7 × 100 = 2500 + 700 ≃ 3200 |
| 3 | 8 | 3.30 GHz | 2500 + 8 × 100 = 2500 + 800 ≃ 3300 |
| 2 | 9 | 3.40 GHz | 2500 + 9 × 100 = 2500 + 900 ≃ 3400 |
| 1 | 10 | 3.50 GHz | 2500 + 10 × 100 = 2500 + 1000 ≃ 3500 |
Practical concerns
While Turbo Boost has the potential to speed up single threaded tasks that are unable to otherwise take advantage of the additional cores, it is very rare to see the full advantage in practice. At issue is the need for two or three cores to be inactive to reach the two or one core active turbo speeds; Windows will take a single thread and run 25% of it on each of four cores instead of putting it all on one core.[citation needed] While, since it is a single thread, there is only one core active at a time, the other cores need time to go to sleep and allow the running core to boost up. As a result, the single-core speed is not seen and the two-core speed is rarely seen unless processor affinity has been set to a single core.[6] Technology like core parking[7] will need to evolve before full benefit is seen.
While the above may be true for quad-core processors, the dual-core i7-2620M (2.7GHz Sandy Bridge) processor will run with both cores in Turbo Boost indefinitely in a properly designed system.
In Windows 7, the default power options are actually set to prevent any physical core from parking, perhaps due to performance considerations when dealing with chips where parking might introduce delay and responsiveness problems. These hidden settings can be revealed and then modified by the user.[8]
See also
References
- ^ a b c d http://www.intel.com/technology/turboboost/
- ^
Molka, Daniel (2009). Memory Performance and Cache Coherency Effects on an Intel Nehalem Multiprocessor System. 18th International Conference on Parallel Architectures and Compilation Techniques. pp. 261–270. doi:http://doi.ieeecomputersociety.org/10.1109/PACT.2009.22. ISBN 978-0-7695-3771-9. Retrieved 2010-05-13.
[...] processors based on the Nehalem microarchitecture feature a dynamic overclocking mechanism (Intel Turbo Boost Technology) that allows the processor to raise core frequencies as long as the thermal limit is not exceeded.
{{cite conference}}: Check|doi=value (help); Cite has empty unknown parameter:|conferenceurl=(help); External link in|doi=|coauthors=ignored (|author=suggested) (help); Unknown parameter|month=ignored (help) - ^
"Intel Turbo Boost Technology in Intel Core Microarchitecture (Nehalem) Based Processors" (PDF). Intel Corporation. 2008. p. 5. Retrieved 2010-05-13.
Intel Core Microarchitecture (Nehalem) based processors incorporate a new feature: Intel Turbo Boost technology.
{{cite web}}: More than one of|pages=and|page=specified (help); Unknown parameter|month=ignored (help) - ^
"Intel Launches Fastest Processor on the Planet" (Press release). Intel. 2008-11-17. Retrieved 2010-05-13.
Intel Corporation introduced its most advanced desktop processor ever, the Intel Core i7 processor. The Core i7 processor is the first member of a new family of Nehalem processor designs [...]
- ^ Tech ARP - Intel Dynamic Acceleration
- ^ Intel’s Turbo Boost: Lynnfield Gets Afterburners : Intel Core i5 And Core i7: Intel’s Mainstream Magnum Opus
- ^ Core Parking in Windows Server 2008 R2 and Windows 7 | Dr. Dobb's and Intel Go Parallel Programming
- ^ Masaki Iwata - Windows 7 Core Parking on how to use