sendfile(2) SF_NOPUSH flag proposal

[Bill Fenner]

>1) use TF_NOPUSH to coalesce the header and the first file part 
>   or the last file part and the trailer as Matthew Dillon suggested;

Is this really necessary?

>2) use the same TF_NOPUSH to postpone the sending partial packet while
>   a reading file page from the disk;

PRUS_MORETOCOME does this too, and is quite a bit less hacky.

>3) and use PRUS_MORETOCOME to avoid partial packet after EAGAIN
>   on non-blocking socket.

Yup.

  Bill