Re: [PATCH] zero^H^H^H^Hsingle copy pipe

["David S. Miller" <davem@redhat.com>]

Ben LaHaise writes:
 > and then use a map_mm_kiobuf (which is
 > map_user_kiobuf but with an mm parameter) for the portion of the buffer
 > that's currently being copied.  That improves code reuse and gives us a
 > few primatives that are quite useful elsewhere.

If it has roughly the same cost as Manfred's copy_user thing, it is
therefore roughly equivalent.

If this map_mm_kiobuf() thing would cost more (I think it would
because it would be using kiobufs when for this case there is
absolutely no need for them) then why?  "It's a clean interface
everyone can use" is not an acceptable answer when the clean interface
costs significantly more than the straightforward approach.

Later,
David S. Miller
davem@redhat.com