64-bit 時代的重要性 (updated)

[h2o]

windows xp 64 出左一段時間, vista 又會下年出, 64 bit 既年代即將來臨,
咁點解 64bit 系咁重要呢?

依家32-bit 既 windows (eg. 2000, xp) 最大只系 support 到 4GB RAM, 其實不完全正確, 等我解釋一下, 希望大家知多d.


首先講 RAM, 你可以想像系一間好大既貨倉, 地下鋪左好多1尺 x 1尺大既磁磚, 一塊磁磚就系1 byte, 每塊磚都有一個編號, 叫做 memory address.
1GB RAM 就系 2 既 30 次方(可以用 2^30 來代表) = 1,073,741,824 bytes, 4GB RAM = 4,294,967,296 bytes 即系有42億平方尺咁大.

而一個 32-bit 既 cpu 既意思就系同一時間處理 32 bits 咁多既貨, 用黎放落個 RAM 到 = 2^32 = 4,294,967,296 bytes.

一個 32-bit 既 windows 世界裡面, 每個 programme 都會有 "virtual" 4GB memory space. 呢 4GB 既 space 會分開一半, 有 2GB 俾 system 用, 另外 2GB 就系俾 programme 用. 每個 programme 都可以擁有自己既 2GB 空間, 但系所有 programmes 都會用同一個 2GB system 空間黎用.
如果你部機有4GB RAM, 咁呢個 virtual space 會分哂落實則既 RAM 到.


例如 maya rendering 1個大場景, cpu 會去到100%, 代表佢搬緊 2GB 既貨入貨倉 (實則系 1.6 GB, 呢個系 maya 認為最佳既效能), render 到一半時如果貨倉滿左, 佢就會嘗試搬番d 舊貨出黎, 但系呢個動作好危險, 好易整林d貨, 即系我地成日預到爆 RAM 然後 error 既情況.

講多少少, 如果你部機得1GB RAM 會點, 呢個時候就會用個 harddisk 做個緩沖, 借 harddisk 1GB 位置暫存 memory. 但系 harddisk 既速度比 RAM 慢好多, 我當 harddisk 速度系8ms, RAM 系 8ns..... 即系相差 1百萬倍
所以我地做 rendering 一定要 optimize 個 scene, 正因為系咁, 所以 renderman 可以 optimize memory 呢個 setting 系好剎食!


其實由 windows 2000 開始已經可以 support 32GB RAM, 不過系高級既 server 版, 個操作模式依然系有2GB 預留俾 system 用. 另外同一時間只可以處理 2GB 既貨, 之不過系個貨倉大左, 多左d 位黎擺野, 唔使每次搬出搬入.

Windows 2000 Memory Support:
Windows 2000 Professional and Server - 4 GB
Windows 2000 Advanced Server - 8 GB
Windows 2000 Datacenter Server - 32 GB

Windows XP Pro & Windows Server 2003 Memory Support:
Windows XP Pro and Windows Server 2003 - 4 GB
Windows Server 2003, Enterprise Edition - 32 GB
Windows Server 2003, Datacenter Edition - 64 GB


另外microsoft 都有方法解決呢個問題, 佢會 set 3GB 俾 programme 用, 剩余 1GB 俾 system 用, 不過 maya 6 & 7 仍然系 limit 左 1.6GB 左右. Maya 8 32-bit 就冇問題, 可以用到 3GB memory.


咁64-bit cpu 又會點呢? 即系同時可以處理 18,446,744,073,709,551,616 bytes (18 billion GB) 咁多囉! 理論系咁, 不過實際 windows xp 64 系 limit 左 128GB (2^37 bytes) 既 physical memory & 16TB (2^44 bytes) 既 virtual memory. Microsoft 話呢個 limit 系增加 hardware 既兼容性. 但系坊間好多底板仲系 support 4GB RAM 咋, 買個時要小心d 喇!


順手提一提 maya 64 bit 既功能:

當然 maximum memory 多過 4GB, 實際視乎 system 既 setting

用左 SSE2 架構來做浮點運算 (floating point computations)

改用 64-bit 既 code 之後, 效能得到提升 (用同一個 system 分別用 32-bit 同 64-bit render 同一個 scene, 64-bit 快左 4-8%)


Reference links:
Memory Support and Windows Operating Systems:
http://www.microsoft.com/whdc/system/pl ... AEmem.mspx

A description of the 4 GB RAM Tuning feature and the Physical Address Extension switch:
http://support.microsoft.com/kb/291988/

Windows XP SP1 May Not Start with the /3GB or /USERVA Switch:
http://support.microsoft.com/default.as ... -us;328269

[h2o]

寫完都已經零晨5點, 開始唔知自己做緊乜..... 遲d我會再修訂 -_- zzZZ

我都知寫得差比較難明, 懇請大家原諒, 如有唔明白既地方可以再討論下

thx

[leeho]

寫完都已經零晨5點, 開始唔知自己做緊乜..... 遲d我會再修訂 -_- zzZZ

我都知寫得差比較難明, 懇請大家原諒, 如有唔明白既地方可以再討論下

thx

謝謝 ... 寫得很長盡 ,
windows xp 64 其實我都想裝 但系驚d軟件和硬件找唔到或是未出64bit版 , 如果有d出有d未出 , 咁樣 , 所以我會等到最成熟時候去裝

[HammerChugoh]

cool stuff H20,

not a OS expert and don't want to pretend I am. But I think 32bit linux handle stuff in a similar manner. 1G kernel and 3G user.

And with a 64bit OS running a 32bit binary we got one more G.

And even cooler is, real 64bit binary on 64bit OS, you can malloc up to 500G~(i really don't need that much memory yet)

But then when I look at the note about the work that R&D people did, it seems there are quite a bit of transition work for them to rebuild all the in house tools for us to fully utilize the 64 bit AMD Opteron.

And when we are writing plugin with C, there are in house library and variables that will automatically switch between single and double precision depends on which of the 2 that your plug-in are built for.

[supercat7xx]

但微軟最新的作業系統不知何時才推出, 現有的硬件幾強都無用啊!

[h2o]

windows xp 64 其實我都想裝 但系驚d軟件和硬件找唔到或是未出64bit版 , 如果有d出有d未出 , 咁樣 , 所以我會等到最成熟時候去裝

家庭用戶真系唔好裝 xp64, 佢只不過系過渡產品. 我都用左自己既 render 機黎試, 冇 sound, printer, scanner drivers, 如果涉及到 windows driver 既 software 又系唔 support, 要等 64-bit 版 (eg. Alcohol, 本人的 alcohol 已經 kick 死左, 鏟唔走, update 唔到新version)

等 vista 啦.... d 廠商都系睇住 vista 黎寫 driver, xp64 冇人理架

[choppy]

淺顯易明既比喻!!!thank you~~~

64bit比32bit真系正好多

[Vantage]

好文章緊系要頂一頂！

[h2o]

update 左 windows xp64 RAM limitation 既資料

[flyws]

唔知而家Maya64bit應該用xp sp1好，定系用vista好呢？跟據水哥的文章所講xp 64bit好似用唔過！
最近想換部新機，想請問下Dell?底板o.k.嗎？support over 4GB RAM?用邊種cpu好呢？Intel® Core 2 or Intel® Xeon® 64-bit ，Intel® Core 2 Extreme 好似好貴喎！

[h2o]

咁都俾你搵番呢篇野......

我 keep 住一部機系 32bit xp, 用黎 connect 所有 hardware, 其他做野既 workstation 就行 windows64.

我試過 vista..... 真系好大食, off 左好多冇謂既 windows function, 都去唔番 xp 既食 ram 水平.

砌 xeon 機真系好貴, quad core 已經夠一般 home office 既 freelancer 用, 至於 config 遲d 再 post, 我都要 update 下今個星期既 hardware, 做下功課先.

我知 quadro 開始出新一代喇, 當然我系指 entry level 啦!

[flyws]

window64系咪指xp64bit呀？好似好多driver唔support喎！水哥有冇D好唧motherboard介紹呀，謝謝！

[paus]

64bit Vista driver會較64 bit XP全面.

[h2o]

唉... 兩邊都唔討好

d 廠都唔會出 xp64 既新 driver, 依家系都 support vista 啦, 不過 vista 大食又系死症.....


都系個句, 我用緊 xp64 做野完全冇問題, 基本 drivers 都有既.... sound, display, external HDD/ drives, wacom

只做 2d, 3d 野冇問題, 比 xp32 仲食小左 ram 添, 但系其他 entertainment 唔好諗住有咯, 即系打機, meida-centre 個種..... 但系我用 xp64 聽歌就升頻去 24bit, 又幾好 wow