Does Zero-copy exist in Windows OS?

9
votes

Reading this zero copy article,

Does Zero-copy exist in Windows OS (server 2003, 2008, 2008 R2) ?

1
windowszero-copy

1 Answers

9
votes

Yes, it is supported via the TransmitFile API.

I'm pretty sure that IIS uses this as well.

Whether or not this method does real zero-copy (i.e. doesn't even copy from the file buffers to the socket buffers) is not explicitly mentioned in the documentation. But given the fact that this method is defined in a way that definitely makes it possible, I'd be highly surprised if this were not the case.

The closest the documentation comes to stating it clearly is this paragraph:

[...] TransmitFile achieves its performance gains by sending data directly from the file cache.