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发表于 2008-8-22 11:06:58| 字数 7,603| - 中国–广东 电信
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Posted by zhangyongtao on 2008-8-21 11:32 
这个编辑真菜
明明INTEL的那个CPU（现在被别家收购）才是处理PDA数据的
而另外高通的是处理电话功能的
偏偏要说个相反。 真是要误导多少人啊？
很遗憾，我只能说，确实是我错了，本来我是这样认为的，由于缺少理论依据，在xscale官方网站上看了官方的文档，我才了解过来，这是我的错误，希望能原谅我。
至于转载文章的错误，我也在向该网站反映，毕竟这种错误，对于一个专业网站来说，是不应该发生的。。
以下是我找到的答案，希望，可以使大家明白一点：
Xscale与OMAP的CPU对比之我见
<<Xscale与OMAP的CPU对比>>的出处就是这篇文章某人有失偏颇的翻译...
--- 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
注:
(1) Wizard就是DPD 838
(2) HP6315/MPX220用的CPU就是OMAP 1510
(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,超频时非常有必要的,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,懂CPU原理的,自然清楚
这就是那篇点要...
----------------------
就说说最重要的几点区别:
1)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
2)OMAP850的一个时钟周期能执行8条指令
Xscale则一个时钟周期只能执行4条指令
因此,OMAP850的并行处理能力比Xscale强
如果程序优化得好的,200MHz的OMAP850在效能上可以等于416MHz的XScale
那些SPB Benchmark目前没有这个优化,因此,测试结果没有意义
另外,只针对XSacle的程序用在OMAP850上,也只能变慢一倍
3)耗电,绝对是OMAP850比Xscale少很多-
为Xscale设计的软件,只能让OMAP850在一个时钟周期执行4条指令,当然效能就低了
就按照CPU所用的工艺,Xsacle是0.18的,而OMAP是0.13的
内存而言,Xscale是SD-RAM,OMAP850是DDR-RAM,也是不同的
.....
OMAP用40%的耗能,获得PXA27X 80%的性能,在Phone上,是成功的
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
架构差异,就摆在面前,怎么看就是各位自己决定了
本人从事软件开发,包括嵌入式系统平台,从科研角度出发,使用TI编译器优化的程序,才能在OMAP获得很好的性能
为了兼容,只能牺牲性能,这是不可避免的
全美达的cpu本来就不是X86体系的,为了兼容X86当然性能低下
原理就像模拟器,PS2的CPU很NB吗?怎么现在4G的CPU都无法模拟得好?这就是架构差异的原因.
原文那个仁兄通篇都没有提到过:"OMAP用40%的耗能,获得Xscale pxa27x 80%的性能,在PPC手机上,这就是成功的。"而那个翻译文章里贸
然出现了这样不负责任的话...
1所谓的双核,就是电话模块由专门的一块辅助芯片来负责,与pda功能无关...(这样当然有好处,但是一边打电话一边玩游戏???处理文档???的人也不多吧...用一位仁兄的话
"Omap中的俩个core,一个ARM7用来处理网络，比如通话，短信GPRS等等，另外一个ARM9用来运行WM5。两个CPU采用双口RAM进行通讯。
Xscale 用来做手机的话，需要加上另外一个基带处理器， 如果你需要CDMA， 那就选择 高通的6205；如果需要GSM，可以选择飞利浦、英飞琳或者其他的；如果你需要做高端的3G手机， 可以选择高通的6280（HSDPA） 或者6250 (WCDMA).
因此， OMAP目前只能支持GSM （GPRS，EDGE），而不能支持WCDMA，CDMA 等等其他的制式。
而采用XSCALE + 基带处理器的情况下，要灵活很多，当然，价格也会高一些。
OMAP的双核对于性能来讲，并没有贡献， WM永远运行在Arm9上。
至于说OMAP 200M是的性能 能和Xscale416相媲美，好像是不太可能。 OMAP使用的是ARM公司的标准的core，TI是没有权利修改。 而XScale 是intel修改过的，增加了WMMX，对多媒体的性能有进一步的提升。"
性能上OMAP和Xscale比??没得比...
)
2所谓的wm5系统对其的优化问题..(文章里明确说了因为两个底层硬件平台是完全不同的,所以wm也是用不同的机制去支持两个硬件平台的.不
是说什么单独对ti优化了...The OS builds are completely different and operate and interact with the
hardware in different ways)
3对ti优化的程序运行效率的问题..(所谓优化就是用相应处理器的编译器产生的程序,能针对硬件平台产生高效率的指令现在ppc上流行的通用第三方软件哪些个是专门为ti处理器优化的??)
4处理器的设计问题...(一个周期完成8条指令...看起来比intel翻了一倍,但是处理器的设计就决定了问题没有这么简单...打个比方
,一个积分运算本来可能需要很多条加法指令才能完成,可是如果处理器设计了积分器,则仅需要1条指令就可以完成...再加上不是所有的指令都能并行处理,不是真正双物理核心就没有办法做到的...程序请求一个中断,那cpu就停下所有的事情来处理这个线程,那么这个时候看起来好像同时处理8条指令有优势,但是如果无法并行处理某些指令,那么一个周期8条也是鸡肋...其实这样比纯属胡扯,这个指令指的是cpu内部指令,设计不同的话同样一件事情产生的指令数目也是不同的...所以这样的比较都是没有意义的... xscale的优势还是在性能上,通用测试软件spb benchmark就能说明问题,tcpmp也能说明问题,毕竟很少有程序专门是用ti的编译器编译的,所以成绩还是客观的...总不能说给我怎样的条件我就能提高性能吧??实际应用是广泛的普遍的...退100步说,即便它优化了,200mhz的850能和416mhz的270比???笑话)
5耗电的问题...(如果说"OMAP用40%的耗能,获得Xscale pxa27x 80%的性能"的话那是不是说omap的待机 时间会是xscale的两倍呢???
我待机3天你HTC能用5,6天???所以翻译者的这句话简直没有道理...其实能耗不光是处理器,还有其他原件也同样有功耗,所以最终产品的待机和设计有很大关系,和平台也有很大关系,所以没有见到说什么用omap的处理器的机器比用xscale的待机时间长了好几天的情况.)
6说了这么多,不是非要争个高下,而是不要让某些人的想法就统治了每个人的想法,既然两者都存在就有它的道理,只能说各有优
势...这个区域不是唯性能论的,生产设计成本,功耗,以及集团利益问题都是影响到最终采购方案的...HTC之所以用这个方案想必有它的道理,较低的成本能获得较高的效益何乐不为???再次,你知道有个intel,有个ti,我知道也有,但是不是所有人都知道呢???其实大部分用户根本不了解什么配置,什么硬件什么系统...都是用来用的,电话好打,短信好发,待机ok,功能完善,外观漂亮那还需要什么呢???所以这个问题可以无视...而且原文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...说的是很客观的,合适的就是好的... |
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