iPad2 新規格與iPad的降價

randyj · 2011-03-03T15:19:10+08:00

iPad2的新聞從凌晨就開始關注主要的變更前後鏡頭重量變輕體積變薄多色的Smart Cover可更換處理器由A4升級為A5雙核而作業系統似乎不變小弟的問題來了由於系統不變情況下iPad2還是跟一代一樣一樣不支援多工(並不是雙核心不支援多工，而是iOS目前的運作非多工方式運作)系統與軟體不支援多工會有什麼影響？通常表示多核心的處理器效能升級將不明顯以目前app多數軟體通常比較耗資源的是I/O處理(還有OOM的問題：out of memory)而非cpu資榞使用也就是當CPU效能無法單核心就吃滿情況下雙核心可能會無法帶來可見的效能(更何況大多APP軟體並不支援多thread運作情況下)多工的解釋已回文在24樓http://www.mobile01.com/topicdetail.php?f=563&t=2038139&p=3#28289520這也是為什麼前幾年CPU在單核升級雙核時很多軟體測出來的結果3.0單核常常跑得比2.0雙核快得多時脈高比雙核心有用並不是唱衰iPad2(因為iPad2確實比起1仍有更多吸引apple迷的白色、輕薄、smart cover、鏡頭)而是如果A4升級到A5處理器的差別不是這麼大(都是1G MHZ)現在一代降價，也給各位一個參考逢低買進其實一代該是可以進場的時候了(撿二手^^)

shimingc

19分

41樓

shimingc

個人積分：19分

文章編號：28496272

randyj wrote:
請看拆解圖
最左是音頻編解碼器，再來是陀螺儀
以及共用的微處理器

真的不得不說....唬爛不打草稿..

你這張是iPod Touch 4代的拆解圖，引用自iFixit網站。

http://www.ifixit.com/Teardown/iPod-Touch-4th-Generation-Teardown/3562/3

其中，step 21就是這張圖。

旁邊的說明是：
On the far left is a 338S0859 chip. It's similar to the Cirrus Logic audio codec of the iPhone 4 (338S0589).
The new AGD8 2032 gyroscope is very similar to that one of the iPhone 4.
The 2032 33DH chip is found next to the gyroscope. It seems this chip was packaged in the same die with the gyroscope in the iPhone 4.

中間跟右邊都是陀螺儀用的，在iPhone4裡頭是封裝在同一顆的。

你也可以參考另一家更專業的分析公司：
http://www.ubmtechinsights.com/uploadedImages/Public_Website/Content_-_Primary/Investigative_Analysis/2010/Apple_-_Looking_at_the_new_Apple_iPods/apple-ipod-touch-web.jpg

這張圖左邊的iPod晶片列表，最下面三顆就是你這張圖片中的這三顆的用途，不過他們的詳細報告是要付費的。

你認為我還需要你手上那些有問題的paper嗎?

randyj

174分

樓主

randyj

個人積分：174分

文章編號：28498586

shimingc wrote:
真的不得不說....唬爛不打草稿.........(恕刪)

這塊的模組設計
ip4跟 ipod touch4是一樣的
內嵌式微處理器確實現在有封裝在同一顆的趨勢
不管是繪圖核心、數位訊號處理核心、微處理器核心
不少都跟記憶體與邏輯電路在單一晶片上
System on Chip已成為21世紀技術的主流
在38樓的文章中，小弟也指出ipad ip4 ipodtouch4這幾個裝置
多處電路設定模組是一樣的

若都已經提供正確資訊給您
您的口氣都還是如此
我個人也保留您這句話
"唬爛不打草稿"
法律追溯權

現在已通知站方人員
希望可以設定為保護文章無法修改

shimingc

19分

43樓

shimingc

個人積分：19分

文章編號：28499399

randyj wrote:
這塊的模組設計
ip...(恕刪)

你講的是愈來愈荒謬了，提醒你一下，你現在要講的是，iPhone把Audio晶片的處理器放到陀螺儀的晶片裡頭喔。

你先去查一查廠商的說明再來掰吧。

randyj

174分

樓主

randyj

個人積分：174分

文章編號：28499843

shimingc wrote:
你講的是愈來愈荒謬了，提醒你一下，你現在要講的是，iPhone把Audio晶片的處理器放到陀螺儀的晶片裡頭喔。

你先去查一查廠商的說明再來掰吧。

我先引述我之前的內容

1、A4單核心CPU是否可同時完成兩個以上的執行緒(強調是要同時)？
我的答案是無法同時，頂多只是快速切換完成多道執行緒的結果，讓您有同時多工的感覺

2、各個週邊的晶片處是否有內建process core可處理運算？
我的答案是肯定的，但在部份Chip只有低時脈的處理單元

3、回到第一點，若無法"同時"完成，A4單核心在iOS那還能算不算是多工？
這個解讀看人，要說是多工也可，也可以說不是，因為背景服務與正在執行中的App
也只是來回切換執行緒去完成任務，以達到所謂的軟體式的多工，而非硬體上的多工
軟體式的多工，也是部份人說的假多工

4、iOS為了讓單核心也有好的表現，僅提供部份較不佔資源的背景服務可供背景行
這是目前的iOS的架構，也是為什麼小弟說目前的iOS架構，
A5雙核心只對單App使用大量執行緒可提高工作效率
否之，若軟體開發業者無大量使用執行緒
目前的iPad2的CPU時脈是跟1代一樣的
可看見的效能是不明顯的

這也是小弟多次提出，但部份您說這是有問題的內容

再換個方向想
未來在雙核或更多核心的攜帶式系統(例：iPad2、iPad3、iPohne4之後的後代)
軟體開發業者可以大量運用執行緒來增加效能
甚至iOS之後的某個版本
會改為支援多核為主的架構
也許也不再支援單核心的設備
或許也可以猜想得到的

另外共用的微處理器若被某一個晶片整合
那也可能是其它的晶片有另外的運算單元

以上不再回覆
部份爭議內容，小弟也考量給第三方單位處理

shimingc

19分

45樓

shimingc

個人積分：19分

文章編號：28503214

randyj wrote:
我先引述我之前的內容

1、A4單核心CPU是否可同時完成兩個以上的執行緒(強調是要同時)？
我的答案是無法同時，頂多只是快速切換完成多道執行緒的結果，讓您有同時多工的感覺

這沒什麼好說的，這本來就是分時多工的基本觀念，拿PC來說，multitask/multithread的系統早就存在，但個人電腦上，多核心的CPU也不過是最近幾年才出現。

2、各個週邊的晶片處是否有內建process core可處理運算？
我的答案是肯定的，但在部份Chip只有低時脈的處理單元

這絕對是否定的，獨立運作的子系統代表的是嵌入另一台電腦，個人設備根本不存在這樣的東西。

3、回到第一點，若無法"同時"完成，A4單核心在iOS那還能算不算是多工？
這個解讀看人，要說是多工也可，也可以說不是，因為背景服務與正在執行中的App
也只是來回切換執行緒去完成任務，以達到所謂的軟體式的多工，而非硬體上的多工
軟體式的多工，也是部份人說的假多工

同1，multitask是OS設計的issue，跟CPU沒有關係，單核心執行多工OS早就存在幾十年，沒什麼假多工的論點，除非講的人不懂。

4、iOS為了讓單核心也有好的表現，僅提供部份較不佔資源的背景服務可供背景行
這是目前的iOS的架構，也是為什麼小弟說目前的iOS架構，
A5雙核心只對單App使用大量執行緒可提高工作效率
否之，若軟體開發業者無大量使用執行緒
目前的iPad2的CPU時脈是跟1代一樣的
可看見的效能是不明顯的

這根本是胡說八道。

另外共用的微處理器若被某一個晶片整合
那也可能是其它的晶片有另外的運算單元

不要可能來可能去，根本不存在這樣的東西。

以上不再回覆
部份爭議內容，小弟也考量給第三方單位處理

這是最好的，你堅持的說法根本找不到佐證，連post 拆解圖都被抓包根本是張冠李戴，繼續post下去。是會誤導其他人的。

夢想很貴

0分

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夢想很貴

個人積分：0分

文章編號：28507301

Differences Between Multithreading and Multitasking for Programmers

Background
A multicore system is a single-processor CPU that contains two or more cores, with each core housing independent microprocessors. A multicore microprocessor performs multiprocessing in a single physical package. Multicore systems share computing resources that are often duplicated in multiprocessor systems, such as the L2 cache and front-side bus.

Multicore systems provide performance that is similar to multiprocessor systems but often at a significantly lower cost because a motherboard with support for multiple processors, such as multiple processor sockets, is not required.
Multitasking
In computing, multitasking is a method by which multiple tasks, also known as processes, share common processing resources such as a CPU. With a multitasking OS, such as Windows XP, you can simultaneously run multiple applications. Multitasking refers to the ability of the OS to quickly switch between each computing task to give the impression the different applications are executing multiple actions simultaneously.

As CPU clock speeds have increased steadily over time, not only do applications run faster, but OSs can switch between applications more quickly. This provides better overall performance. Many actions can happen at once on a computer, and individual applications can run faster.

Single Core
In the case of a computer with a single CPU core, only one task runs at any point in time, meaning that the CPU is actively executing instructions for that task. Multitasking solves this problem by scheduling which task may run at any given time and when another waiting task gets a turn.

Multicore
When running on a multicore system, multitasking OSs can truly execute multiple tasks concurrently. The multiple computing engines work independently on different tasks.

For example, on a dual-core system, four applications - such as word processing, e-mail, Web browsing, and antivirus software - can each access a separate processor core at the same time. You can multitask by checking e-mail and typing a letter simultaneously, thus improving overall performance for applications.

The OS executes multiple applications more efficiently by splitting the different applications, or processes, between the separate CPU cores. The computer can spread the work - each core is managing and switching through half as many applications as before - and deliver better overall throughput and performance. In effect, the applications are running in parallel.

Multithreading
Multithreading extends the idea of multitasking into applications, so you can subdivide specific operations within a single application into individual threads. Each of the threads can run in parallel. The OS divides processing time not only among different applications, but also among each thread within an application.

In a multithreaded National Instruments LabVIEW program, an example application might be divided into four threads - a user interface thread, a data acquisition thread, network communication, and a logging thread. You can prioritize each of these so that they operate independently. Thus, in multithreaded applications, multiple tasks can progress in parallel with other applications that are running on the system.

Applications that take advantage of multithreading have numerous benefits, including the following:

More efficient CPU use
Better system reliability
Improved performance on multiprocessor computers
In many applications, you make synchronous calls to resources, such as instruments. These instrument calls often take a long time to complete. In a single-threaded application, a synchronous call effectively blocks, or prevents, any other task within the application from executing until the operation completes. Multithreading prevents this blocking.

While the synchronous call runs on one thread, other parts of the program that do not depend on this call run on different threads. Execution of the application progresses instead of stalling until the synchronous call completes. In this way, a multithreaded application maximizes the efficiency of the CPU because it does not idle if any thread of the application is ready to run.

Multithreading with LabVIEW
LabVIEW automatically divides each application into multiple execution threads. The complex tasks of thread management are transparently built into the LabVIEW execution system.

Multitasking in LabVIEW
LabVIEW uses preemptive multithreading on OSs that offer this feature. LabVIEW also uses cooperative multithreading. OSs and processors with preemptive multithreading employ a limited number of threads, so in certain cases, these systems return to using cooperative multithreading.

The execution system preemptively multitasks VIs using threads. However, a limited number of threads are available. For highly parallel applications, the execution system uses cooperative multitasking when available threads are busy. Also, the OS handles preemptive multitasking between the application and other tasks.