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Re: Software optimization resources [message #30535 is a reply to message #30530]

Fri, 07 January 2011 11:01

dolik.rce
Messages: 1789
Registered: August 2008
Location: Czech Republic

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Didier wrote on Thu, 06 January 2011 22:52

Hi Novo,

I haven't tried the samples you are talking about but for special assembler functions to work (SSE, or whatever, ....) the memory has to be aligned on 4 bytes or 64 bytes or 128 bytes or more maybe.
The alignement depends on the assembler instructions used.

If the memory is not aligned correctly either you get bad results or just poor execution timings.

Maybe this is what happens in you're case

Hi Didier,
I believe you react on my post, even though I'm not Novo Wink

The asmlib functions take the alignment into consideration. Their internals first take care of the unaligned part using clasic instructions and then process the rest using SSE or whatever available.

After some more thinking I believe that the real reason why there was no noticeable change was badly chosen benchmark. There was probably majority of the time spent in other functions than memory and string handling. I will try again with better constructed test code.

Honza

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