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原帖地址：http://www.raspberrypi.org/archives/2008
RPi 加强模式：免费的50％性能提升
原文大意：
自从RPi发布，我们就一直提供通过修改config.txt的方法进行RPi超频。提高电压能够提供更大的超频空间，但出于保证芯片的使用寿命，这将使RPi失去保修。我们在BCM2835芯片里面做了手脚，以便留意RPi是否进有过超电压运行。
我们做了很多工作，研究了电压、温度对于芯片寿命的影响，现在能够提供一种“加强模式”——通过CPU频率驱动动态控制超频频率和电压提高芯片性能，而且这完全不影响保修。系统繁忙时会自动进行超频，当芯片内部温度接近85度时，超频模式会被自动进行限制，这意味着‘超频模式’对芯片寿命的影响几乎是察觉不到的。
现在你可以从5种超频设置中选择一种，最高的运行频率将达到1GHz。超频后最终的稳定运行频率与你的RPi体制（拼人品了）、以及电源供电质量有密切联系。我们建议使用Quake3（雷神之锤3）进行压力测试，检测你的Pi能够稳定运行在哪个超频频率下。如果你选择的超频频率过高，Pi可能启动失败，请选择一个低一些的频率测试。（感觉像x86CPU超频，基本上人品很重要）
与默认700MHz运行的Pi相比，装载1GHz加强模式镜像的Pi将有大约52％的整数性能提升和64％的浮点性能提升以及55％内存性能提升。
［两张表就不翻了］
新固件的其他变化
添加温度和频率小工具
降低USB中断频率，提高大约10％整体性能（不明白是USB还是整块板子）
RTL8188US方案的WIFI驱动已经整合
提高音频质量
添加了SmartSim和RenguinsPuzzle两款软件
如果你在使用老的wheezy镜像，你可以使用| “sudo apt-get update && sudo apt-get upgrade” |
升级这些新的特性。
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Introducing turbo mode: up to 50% more performance for free
Posted on September 19, 2012 by eben
Since launch, we’ve supported overclocking and overvolting your Raspberry Pi by editing config.txt. Overvolting provided more overclocking headroom, but voided your warranty because we were concerned it would decrease the lifetime of the SoC; we set a sticky bit inside BCM2835 to allow us to spot boards which have been overvolted.
We’ve been doing a lot of work to understand the impact of voltage and temperature on lifetime, and are now able to offer a “turbo mode”, which dynamically enables overclock and overvolt under the control of a cpufreq driver, without affecting your warranty. We are happy that the combination of only applying turbo when busy, and limiting turbo when the BCM2835′s internal temperature reaches 85°C, means there will be no measurable reduction in the lifetime of your Raspberry Pi.
You can now choose from one of five overclock presets in raspi-config, the highest of which runs the ARM at 1GHz. The level of stable overclock you can achieve will depend on your specific Pi and on the quality of your power supply; we suggest that Quake 3 is a good stress test for checking if a particular level is completely stable. If you choose too high an overclock, your Pi may fail to boot, in which case holding down the shift key during boot up will disable the overclock for that boot, allowing you to select a lower level.
What does this mean? Comparing the new image with 1GHz turbo enabled, against the previous image at 700MHz, nbench reports 52% faster on integer, 64% faster on floating point and 55% faster on memory.
Previous image (2012-08-16-wheezy-raspbian):BYTEmark* Native Mode Benchmark ver. 2 (10/95)Index-split by Andrew D. Balsa (11/97)Linux/Unix* port by Uwe F. Mayer (12/96,11/97)TEST : Iterations/sec. : Old Index : New Index: : Pentium 90* : AMD K6/233*--------------------:------------------:-------------:------------NUMERIC SORT : 222.08 : 5.70 : 1.87STRING SORT : 31.659 : 14.15 : 2.19BITFIELD : 7.1294e+07 : 12.23 : 2.55FP EMULATION : 44.808 : 21.50 : 4.96FOURIER : 2188.1 : 2.49 : 1.40ASSIGNMENT : 2.6545 : 10.10 : 2.62IDEA : 671.41 : 10.27 : 3.05HUFFMAN : 414.2 : 11.49 : 3.67NEURAL NET : 2.9586 : 4.75 : 2.00LU DECOMPOSITION : 77.374 : 4.01 : 2.89=====================ORIGINAL BYTEMARK RESULTS=====================INTEGER INDEX : 11.414FLOATING-POINT INDEX: 3.619Baseline (MSDOS*) : Pentium* 90, 256 KB L2-cache, ...=========================LINUX DATA BELOW==========================CPU  2 Cache :OS : Linux 3.1.9+C compiler : arm-linux-gnueabihf-gcclibc : staticMEMORY INDEX : 2.447INTEGER INDEX : 3.192FLOATING-POINT INDEX: 2.007Baseline (LINUX) : AMD K6/233*, 512 KB L2-cache, gcc 2.7.2.3, ..* Trademarks are property of their respective holder.
New image, with 1GHz turbo enabled:BYTEmark* Native Mode Benchmark ver. 2 (10/95)Index-split by Andrew D. Balsa (11/97)Linux/Unix* port by Uwe F. Mayer (12/96,11/97)TEST : Iterations/sec. : Old Index : New Index: : Pentium 90* : AMD K6/233*--------------------:------------------:-------------:------------NUMERIC SORT : 340.8 : 8.74 : 2.87STRING SORT : 47.52 : 21.23 : 3.29BITFIELD : 1.05e+08 : 18.01 : 3.76FP EMULATION : 66.32 : 31.82 : 7.34FOURIER : 3431 : 3.90 : 2.19ASSIGNMENT : 4.5311 : 17.24 : 4.47IDEA : 991.67 : 15.17 : 4.50HUFFMAN : 615.08 : 17.06 : 5.45NEURAL NET : 4.76 : 7.65 : 3.22LU DECOMPOSITION : 135.12 : 7.00 : 5.05=====================ORIGINAL BYTEMARK RESULTS=====================INTEGER INDEX : 17.356FLOATING-POINT INDEX: 5.933Baseline (MSDOS*) : Pentium* 90, 256 KB L2-cache, ...=========================LINUX DATA BELOW==========================CPU 2 Cache :OS : Linux 3.2.27+C compiler : arm-linux-gnueabihf-gcclibc : staticMEMORY INDEX : 3.810INTEGER INDEX : 4.768FLOATING-POINT INDEX: 3.291Baseline (LINUX) : AMD K6/233*, 512 KB L2-cache, gcc 2.7.2.3, ..* Trademarks are property of their respective holder.
Other changes to the latest firmware include:
Temperature and frequency widgets
You can enable a core temperature widget for the lxde taskbar to see how close to 85°C you get (in the UK, it’s not very), and a cpufreq widget that will show the current ARM frequency when you hover over it. See here for more details.
USB interrupt rate reduction
We have enabled Gordon’s “FIQ Fix” in the USB driver, which reduces the USB interrupt rate, improving general performance by about 10%.
WiFi is now supported out of the box
If your WiFi driver is supported by the default linux tree, or is based on the popular RTL8188CUS chipset, then WiFi should work out of the box. Boot the image with the WiFi dongle plugged in (a powered hub is recommended). Run startx and select “WiFi Config”. You can scan for wireless networks and enter your wireless password and connect from the GUI. No need to install additional packages or scripts.
Improved analogue audio
Analogue audio quality has been improved.
Extra software installed by default
SmartSim and PenguinsPuzzle are pre-installed.
If you are using an older wheezy image, you can upgrade: “sudo apt-get update && sudo apt-get upgrade” will get almost all these improvements.
Thanks to MrEngman for his amazing work supporting users with various WiFi dongle, Dorian Peake for the cpufreq and temperature drivers, and Dmitry Dudkin for his work on the USB and SD card drivers.
Alex has started a forum thread for further discussion – pile in! |
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发表于 2012-9-19 22:42:40
发表于 2012-9-19 22:57:51
