fast bcopy...

Andrew Reilly areilly at
Thu May 3 23:44:33 UTC 2012

On Wed, May 02, 2012 at 08:25:57PM +0200, Luigi Rizzo wrote:
> as part of my netmap investigations, i was looking at how
> expensive are memory copies, and here are a couple of findings
> (first one is obvious, the second one less so)

Most C compilers (well, the ones I regularly use) inline small,
constant-length memcpy operations of the sort you're describing
here.  I would expect techniques like that to beat any amount of
hand-tuning in a elf-linkage bcopy subroutine.

Sure, you want a good implementation for your variable-length
copies, and data layout and alignment is tremendously important
these days, so there's no single silver bullet here.



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