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   comp.lang.asm.x86      Ahh, the lost art of x86 assembly      4,675 messages   

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   Message 3,081 of 4,675   
   aen@nospicedham.spamtrap.com to amc96@nospicedham.cam.ac.uk   
   Re: more cyles   
   23 Nov 17 17:22:32   
   
   On Thu, 23 Nov 2017 10:00:29 +0000, Andrew Cooper   
    wrote:   
   >...   
   >This use of rdtsc isn't accurate.  It will be reordered in the pipeline   
   >with the content you are trying to time.   
   >   
   >If you have rdtscp available, use that.  It specifically has fencing   
   >properties to prevent reordering.   
   >   
   Since I only use RDTSC at the start and end of the code, and it runs   
   12 seconds that will not add to the timing at all, but yeah using it   
   is an old habit from Pentium days, I will switch to RDTSP.   
   --   
   aen   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

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