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TI OMAP850 vs Intel Xscale 416MHz HTC选择195MHz CPU的原因
大致翻译说明:
(1) Wizard就是DPD 838
(2) HP6315/MPX220用的CPU就是OMAP 1510
1510,只有一个ARM9核心处理器,只是内建DSP处理器而已
850则还有ARM7处理器和DSP处理器,还有2D加速和Java硬件加速,性能不能相比的
(3)OMAP850最高稳定超频速度是:276MHz (OMAPClock) 但是此时的GSM系统出现不稳定,会出现GSM无信号,除此以外并无其他问题,PDA功能仍然可正常工作.因此最高可靠超频速度建议为:264MHz
(4)DPD830(S200) JBanchMark2 分数 比 ATOM要高
(5)使用TCPMP播放高速率视频文件时,超频是非常有必要的,一般240MHz可以满足需要
(6)超频到264MHz后,整数加法运算性能超越PXA270-416MHz,但是浮点运算,依然落后
(7)OMAP850是8条流水线,Xscale是4条,这个是有好处,也有坏处的
OMAP850的并行处理能力比Xscale强
如果程序优化得好的,200MHz的OMAP850在效能上可以接近于416MHz的XScale
那些SPB Benchmark目前没有这个优化,因此,测试结果没有太大意义
另外,只针对XSacle的程序用在OMAP850上,也只能变慢不少的
(8)OMAP 850是双核心的,但有别与PC X86上AMD X2,Pentium D这类
OMAP850是2个不同的物理CPU组成的
它有2个核心,一个ARM926负责PDA功能,另外的ARM7负责GSM Phone功能的
Xscale则,只有一个核心的ARM9处理器,它负责全部事情的处理
当GSM和PDA同时工作时,OMAP850的效能就完全发挥出来了
在PPC Phone上,电话接通下,再执行其他任务,PXA的性能将明显下降,OMAP就不会
OMAP的2个Core都是195MHz,分别处理PDA和GSM
所以OMAP只适合在PPC Phone上使用,不使用GSM,OMAP永远只是一个195MHz的低速CPU
(9)耗电,绝对是OMAP850比Xscale少很多
CPU所用的工艺,Xsacle是0.18的,而OMAP是0.13的
(10)就内存而言,Xscale是SD-RAM,OMAP850是R-RAM,也是不同的
总结:
毕竟Xscale与OMAP的架构是完全不同的
用针对Xscale的软件去衡量OMAP850的性能,也是不合理的
OMAP850是集成了基带处理器的数字系统,决定了它需要用在移动通讯领域的
你不可能在纯PDA上看见OMAP850的踪影
HTC新的WM5手机,大部分都是OMAP850,没见了Xscale的影子,因为WM5为TI OMAP做了优化,用起来不会让你感觉到慢的
想玩GBA,PS等模拟器的人,OMAP850是不合适的,其实就PPC玩模拟器的价值也不大,极其不方便的操作键盘,会很有趣?最多是演示一下而已.而针对PPC开发的游戏,软件,用OMAP850,你是不会觉得有什么缓慢的地方,最多必要时超频一下即可.
耗电始终是PPC的一个重要问题
OMAP用40%的耗能,获得PXA27X 80%的性能,在PPC Phone上,是成功的!
很多喜欢把omap850与intel的Xscale做比较，前者是195MHZ，后者是416MHZ，多数人理解成为Xscale会更快，更强。这里我找了一个资料参考后做了一下对比：
1、omap850的双核心的，但不同于PC是的双核处理器。OMAP850是2个不同的物理CPU组成的,一个ARM926负责PDA功能,另外的ARM7负责GSM电话功能，而Xscale则只有一个ARM9处理器,它负责处理全部事情
2、omap850的一个时钟周期能执行8条指令，而Xscale则一个时钟周期只能执行4条指令但Xscale的频率比omap850高出一倍，所以这里基本上是处理速度差不多的，其实如果程序优化得好的,195MHz的omap850在效能上可以等于416MHz的XScale，SPB Benchmark目前没有这个优化,因此,测试结果没有太大的意义，此外,针对XSacle的程序在，在omap850上运行,会变慢一倍。
3、这里我们来说说功耗，在PC上intel的CPU因为频率高的关系是耗电大户，这大家都知道，相同PR值的AMD的CPU功耗要比intel的CPU小很多（这里对比的是奔腾D与速龙，酷睿是从移动的PM演变而来，在此不做比较）。同样omap850也有这样的优点，在待机的状态下，只需要10µA的电流即可，830一晚也就耗掉2％-3％的电量。这样的优点是不用多说的，待机二到三天不成问题。在芯片工艺上比较也是这样，Xsacle是0.18的,而OMAP是0.13的。0.18的要比0.13的省电。
4、这里我们再来做个内存类型上的比较。Xscale用的是SD-RAM,OMAP850用的是R-RAM,谁好谁差一些，不用我多说了。
5、omap850更适合在PPC Phone上使用，当GSM和PDA同时工作时,OMAP850的效能就完全发挥出来了，在PPC Phone上,电话接通下,再执行其他任务,Xscale的性能将明显下降,OMAP850就不会.OMAP的2个内核都是195MHz,并分别处理PDA和GSM的功能。所以OMAP适合在PPC Phone上使用。这就是为什么在一些纯PDA上看不到omap的CPU。
说到最后：Omap850的架构与Xscale架构上是不同的，TI的omap850更适合应用在移动通信领域。这就是为什么Dopod的产品大部分TI的omap系列CPU。WM5针对omap850做了优化，这样大家在用的时候不会感觉到慢。omap850内部还有2D加速的单元，这就是为什么omap850比Xscale的图形性能强悍的原因了，从TI的产品结构上来看，omap850是2.5G-2.75G中最好的产品。不要看频率的对比，重要的是分析一下结果
原文
--- OMAP1510 vs OMAP850 ---
With all due respect, this statement is foolish, especially if you don't know the difference between the OMAP 1510 and the OMAP 850. It is possible for a CPU of one architecture to be faster at a lower clock speed than another CPU of a completely different architecture; it all depends of how much work each CPU under comparison can perfrom within a given clock cycle.
Both the OMAP 850 and the OMAP1510 are dual core. Both have a primary ARM core (the 850 has an ARM926 core, the 1510 has an ARM925 core) for the OS, application processing, etc. However, the 1510's 2nd core was simply a C54 DSP, whereas the 850 2nd 'core' is actually a multi-core containing a ARM7 coupled with the C54.
Becuase the 1510 2nd core was only a DSP, it most likely (this is a educated guesss on my part) still required the primary ARM to control the GSM radio, even though the C54 did the work. In the 850, the 2nd 'core' is a completely indepdent unit, which can operate without any need to burden the primary ARM.
Given the above, IMHO it's pretty much a given that the OMAP 850 will outperform the OMAP 1510.
For more information, check out TI's datasheets.
As for comparing the OMAP 850 with an XScale at any speed, I can't say how it will stack up, and I haven't been able to find any OBJECTIVE analyses comparing the two architectures. However, understand that because the XScale is a single core CPU, a good percentage of its processing power, even in 624MHz variant of the chip, is being dedicated to the GSM processing, as that is first and foremost in a PPC phone. In the OMAP 850, this is not an issue; 100% of the primary core's time can be spent on the OS and it's applications. Just becuase it's only rated at 200MHz doesn't necessarily mean it's gonna be a dog.
--- TI OMAP 850 vs INTEL Xscale Bulverde PXA270 416 MHz ---
Can you compare a TI OMAP processor with an Intel processor? In short, no. There are quite a few differences as follows:
• The two chipset and architectures are completely different and it is impossible to compare them directly. The Intel architecture is what is called a single core. One chip is used to run both the radio and Operating System parts of the device. This is how most mobile phones work, and it delivers significantly improved battery management, reliability and product life. TI architecture currently have a two chip solution, where the radio and CPU are separate. This is less battery efficient and they need a faster CPU in order to operate the same way. Windows Mobile has been optimised for both the TI architecture and the Intel architecture, and both chip manufacturers have optimised their hardware accordingly. The OS builds are completely different and operate and interact with the hardware in different ways.
• The TI OMAP 850 chipset is specifically designed to work with Windows Mobile devices. This means that the TI chip can perform some operations in with one command whilst the intel chips require multiple "step-by-step" commands. The up side of this is considerably faster execution of regularly occuring tasks. The down side to this change is that some third party applications which have been written to work with previous versions of windows mobile will still require the "step-by-step" commands and will therefore run more slowly. If these applications are revised to support the TI command set the performance should be equivalent to the intel devices.
• An intel CPU basically executes four commands on each clock cycle - whilst the TI OMAP 850 chipset used in the i-mate™ K-JAM & i-mate™ JAMIn performs eight instructions per clock cycle.
• The TI OMAP 850 has a much lower power consumption (in part due to the slower clock speed) - leading to a considerably better battery life.
Our ultimate intent is to have our devices operating more efficiently with no speed degradation apparent to the end user, and better battery life. This may require the adoption of different chip sets on different i-mate™ devices.
--- OMAP850 Dual Core 200MHz CPU---
I can imagine the cries of dispair when the HTC Wizard was announced last year, that it would be powered by a Texas Instruments ARM processor. This especially after the debacle that was the HP iPAQ h6315. After using the Wizard for a week now, I can say that while the OMAP850 processor on the Wizard is only clocked at 200Mhz, it is speedy enough.
It isn't as fast as the 624Mhz processor on the Axim x50v, but it feels just slightly slower than Jennifer's HTC Magician (which has a 416Mhz Intel XScale PXA272 and a slightly unbloated OS). Put it this way, it feels twice as fast as my old Toshiba e310 with its Intel StrongARM 206Mhz. And that is with the bloated Windows Mobile 5.0 OS.
Specifically the OMAP850 contains two cores, an ARM926 application processor from ARM's family of ARM9E cores and a TI EDGE digital baseband chipset, the TCS3500 (an ARM7MCU coupled with Texas Instruments C54 DSP). Basically the workload of the Wizard (or any mobile device that uses the 850) is thus divided into the two cores (with some shared) as you can see from the diagram below (from Texas Instruments):
The ARM926 core controls the WiFi module, Infrared, LCD, buzzer, SD/MMC flash card and SDIO modules, LCD backlight, U connection, battery, camera, LEDs and GPS (The Wizard doesn't have one).
As Windows Mobile 5.0 is a multi-task processor, processors has to divide up between the phone part of the OS and the PDA part. Receiving a call could slow the device down considerably, but the 3500 DSP is specifically there to deal with GSM calls.
It also controls EDGE data communications. The DSP also handles the AC97 audio controller, SIM card, touch screen controller and part of the Bluetooth (voice), as well as the speakers.
Both of the cores share the load on memory controller, 2D graphic accelerator, keyboard and data Bluetooth.
The only slow down I noticed is when playing DivX encoded videos (above 500kbps and it would stutter) but overclocking to 240Mhz using OmapClock would sort it. Even sophisticated 3D games like Michael Schumacher Racing World Kart 2002 ran well. So don't sweat if the device you want contains a OMAP850.
--- conclusion ---
But speed is a subjective matter, and what may seem okay to me may not be okay for you. You should trial any device to see if it fits. Don't let the stores pester you to purchase something. Stay as long as you want and force them to demo the units you want to purchase and make sure they have a reasonable return/exchange policy should you change your mind
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发表于：2007/11/13 21:03:00 [只看该作者]
