Re: zero-copy TCP

From: Ingo Molnar (mingo@elte.hu)
Date: Mon Sep 04 2000 - 02:54:22 EST


On Mon, 4 Sep 2000 kumon@flab.fujitsu.co.jp wrote:

> The experiment showed the following prefetching could reduce 20-30% of
> csum_partial_copy_generic() execution time.

Please test it and post the numbers. csum_partial_copy_generic() already
does prefetching - the real test would be to check lat_tcp and bw_tcp
numbers over gigabit, with and without this patch applied. (the same
numbers over localhost dont really count.) Eg. we had smart KNI-based
memcpy routines as well, and it turned out that bw_tcp over gigabit
actually got slower. [testing over 100mbit isnt enough obviously because
x86 CPUs csum much faster than that.]

        Ingo

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