Re: Semaphore assembly-code bug

[Andi Kleen]

dean gaudet <dean-list-linux-kernel@xxxxxxxxxx> writes:
> 
> it's worse than that in general -- lea typically goes through the AGU 
> which has either less throughput or longer latency than the ALUs... 
> depending on which x86en.  it's 4 cycles for a lea on p4, vs. 1 for a pop.  
> it's 2 cycles for a lea on k8 vs. 1 for a pop.

On D stepping and later K8 the lea is 1 cycle latency because the
decoder optimizes the lea into an add.

-Andi

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