Re: [問卦] 64位元性能比32位元好多少?消失
: 噓 jengjye: Word length是cpu內處理資料的單位...你還真的不懂哇咧.. 06/04 16:44
: → jengjye: 難怪講的描述亂七八糟 06/04 16:44
: → jengjye: 我們在說32與64位元的差別最根本的就是cpu處理word的長 06/04 16:46
: → jengjye: 度...還有我叫你看計結..不是計概 06/04 16:47
: → jengjye: 最好笑的是你說.net f內的32but cpu處理int64 cpu... 06/04 16:49
: → jengjye: 靠腰這三洨鬼描述啊...不懂不要亂扯好嗎 06/04 16:50
: → jengjye: 32 bit打錯,更正一下不是but 06/04 16:51
講這麼多
實際來一下啊 就用 VB.NET 的code 就好
Dim A1, A2, A3 As Int64
Dim A4 As Integer
A1 = 984578604879
A2 = 62796254716
A3 = 62785487631
Dim aa As Integer = Environment.TickCount
For A4 = 0 To 100000000
A1 = A1 + A2
A1 = A1 - A3
Next
MsgBox(Environment.TickCount - aa)
啊如果跑 x64 就約 62ms
x86 就約 402ms
( i7-4770k @ 4Ghz)
性能差了快七倍
A1、A2、A3 哪一筆沒有超過 32bit?
我再debug給你看一次好了
A1= A1 + A2
x86
EAX=5728885C EBX=0339C938 ECX=0338CE40 EDX=00000000 ESI=0338CE40 EDI=074BE6A8
EIP=01613FD1 ESP=074BE638 EBP=074BE6B4 EFL=00200246
0x074be66c=3D753F4F
A1 = A1 + A2
03123FD1 8B 45 B8 mov eax,dword ptr [ebp-48h]
03123FD4 8B 55 BC mov edx,dword ptr [ebp-44h]
03123FD7 03 45 B0 add eax,dword ptr [ebp-50h]
03123FDA 13 55 B4 adc edx,dword ptr [ebp-4Ch]
03123FDD 71 05 jno 03123FE4
03123FDF E8 FC BF 6D 6F call 727FFFE0
03123FE4 89 45 B8 mov dword ptr [ebp-48h],eax
03123FE7 89 55 BC mov dword ptr [ebp-44h],edx
x64
RAX=0000000000000000 RBX=00000212048BAB78 RCX=0000000005941E1E
RDX=00000212048BA8D8 RSI=00000212048BA4B8 RDI=0000009A08AFD900 R8
=00000212048CB928 R9 =0000000000000000 R10=00007FF5FF5F0018
R11=0000009A08AFD4C0 R12=0000000000000002 R13=0000000000000202
R14=0000000000000037 R15=0000000000000000 RIP=00007FFB47E75F11
RSP=0000009A08AFD880 RBP=0000009A08AFD880 EFL=00000246
0x0000000008afd8f0=000000E53D753F4F
A1 = A1 + A2
00007FFB47E75F11 48 8B 45 70 mov rax,qword ptr [rbp+70h]
00007FFB47E75F15 48 8B 55 68 mov rdx,qword ptr [rbp+68h]
00007FFB47E75F19 48 03 C2 add rax,rdx
00007FFB47E75F1C 71 05 jno 00007FFB47E75F23
00007FFB47E75F1E E8 AD 9A AA 5F call 00007FFBA791F9D0
00007FFB47E75F23 48 89 45 70 mov qword ptr [rbp+70h],rax
-----
你該不會不知道 compiler 就是這樣倒進暫存器的吧....
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※ 編輯: wahaha99 (1.171.183.78), 06/04/2017 17:37:49
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※ 編輯: wahaha99 (1.171.183.78), 06/04/2017 17:39:26
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不看暫存器, 不然要看什麼?
匯流排寬度?
定址能力?
指令集長度? (CISC有固定長度嗎? 而且現在根本都uOP化也沒意義)
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有人說64bit cpu比較快不是看這個啊
我怎麼知道他在說啥
※ 編輯: wahaha99 (1.171.183.78), 06/04/2017 17:46:54
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MSIL 就是要靠 Compiler JIT 處理啊
不然是你去倒喔
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※ 編輯: wahaha99 (1.171.183.78), 06/04/2017 17:48:08
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※ 編輯: wahaha99 (1.171.183.78), 06/04/2017 17:48:54
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你一看就是只知道課本上的東西
而且還過時很久 XDD
還跟 code 無關咧
你用同樣的 asm code 看看能不能用 x86 做 int64 加法啊
為什麼我假日要在這邊幫人上計概啊
(計結咧....明明就計概的程度而已)
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※ 編輯: wahaha99 (1.171.183.78), 06/04/2017 18:14:38
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※ 編輯: wahaha99 (1.171.183.78), 06/04/2017 18:19:08
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