GTX 970 記憶體疑似只吃得到 3.5GB (官方回應) - 3C

在Fermi架構下跑出來的值會超高是因為兩個原因

1.編譯時編成m32的版本，沒辦法吃到4G以上記憶體

2.編譯時編成限定kepler以上架構，導致在fermi上不能跑

所以程式會因為出錯立刻結束，讓執行時間超級短

以至於算出來的頻寬會爆高！！

基本上我是認為程式沒有問題

我幫大家編譯了可以在fermi以後世代的卡上跑的程式

http://goo.gl/v7Ogq6

http://goo.gl/fKGHcp

那個因為不能上傳執行檔，下載後把尾巴的_去掉即可

編譯環境是CUDA 7.0RC，所以需要第二個連結的dll檔案一起下載下來

有漏掉什麼dll的話我在補上來

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補上測試結果

http://i.imgur.com/1gbIaBI.png?1

當存取到末端的記憶體時L2 cache的使用量會整個掉下來

原因我就不清楚了，但底是driver還是OS或是硬體的問題

※ 引述《yummypixza (好吃的披薩)》之銘言：
: NVIDIA Responds to GTX 970 3.5GB Memory Issue | PC Perspective
: http://goo.gl/u8ZxN6
: 以下原文新聞稿, 中文有請翻譯蒟蒻
: ---
: The GeForce GTX 970 is equipped with 4GB of dedicated graphics memory.
: However the 970 has a different configuration of SMs than the 980, and fewer
: crossbar resources to the memory system. To optimally manage memory traffic
: in this configuration, we segment graphics memory into a 3.5GB section and a
: 0.5GB section. The GPU has higher priority access to the 3.5GB section.
: When a game needs less than 3.5GB of video memory per draw command then it
: will only access the first partition, and 3rd party applications that measure
: memory usage will report 3.5GB of memory in use on GTX 970, but may report
: more for GTX 980 if there is more memory used by other commands. When a game
: requires more than 3.5GB of memory then we use both segments.
: We understand there have been some questions about how the GTX 970 will
: perform when it accesses the 0.5GB memory segment. The best way to test that
: is to look at game performance. Compare a GTX 980 to a 970 on a game that
: uses less than 3.5GB. Then turn up the settings so the game needs more than
: 3.5GB and compare 980 and 970 performance again.
: ---
: 官方回應出來了
: 簡單來說就是他們的硬體設計執意如此
: "It's by design, not a bug"
: 雖然他們自己說實際上在存取最後0.5GB的效能遞減並不嚴重
: 但是實際上真的會把4GB都塞到炸掉的人應該也大都不是普通人了...
: 到底最後大家買不買帳就(ry
: #ramgate
: edit: 將來源網址縮址 :P

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