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SubjectRe: zero-copy TCP fileserving
> no CPU in the world has memory writes for free! i'll rephrase if its
> hard to understand - the _performance_ effect is not "twice the time" but
> relative to the cpu/bus speed, but the _absolute_ time spent is (+/-
> depending on bus design).

If the CPU can queue posted writes for the data and is still able to feed
itself without stalling, and there is enough bandwidth left for any other
bus masters _in the unlikely event it hits main memory_ then the write is
pretty cheap. Since we are going to want the data again for the actual
I/O transaction in most cases its extremely close to zero cost.


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