x86asm.net

kt.chocofudge · Joined: 09 Jul 2009 Posts: 1

Hi,
I am an undergrad student newly introduced to the x86 ISA.

I am curious: Given an instruction Eg: MOV, It has several variants as far as data movement is concerned.

How different will the power dissipation numbers be for two different variants of the same instruction?
1) MOV R1, R2
2) MOV R1, MEM ....?

Where can I get information on this?

Thanks.

MazeGen · Site Admin Joined: 05 Sep 2007 Posts: 98 Location: .cz

Hello kt.chocofudge,

if you mean how much slower is memory operand access, it depends on many factors. If it is in L1 cache, it should be as fast as register operand. If it is not cached, it tooks longer time. And if the memory was paged out, it takes a lot of time.

I suggest Agner Fog's optimization manuals for further reading.