Re: File copy system call proposal

From: Quinn Harris (
Date: Sat Dec 08 2001 - 23:56:25 EST

On Sat, 2001-12-08 at 17:19, H. Peter Anvin wrote:
> One thing that one could do for an in-kernel copy is to extend
> sendfile() to support any kind of file descriptor. That'd be a very
> clean way to do it.

I think the best thing would be to extend generic_file_write
(mm/filemap.c) to recognize if its writing a complete page to disk in
which case it will not duplicate that page. (Issues with getting the
buffer cache to support this remain.) This should make either the
mmap/write or sendfile aproach be zero-copy. I am given the impression
that this is just what the TCP/IP version of write does to make it

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This archive was generated by hypermail 2b29 : Sat Dec 15 2001 - 21:00:14 EST