Re: sendmsg blocking with sendtimeout vs. non-blocking

[Jim Rees <rees@umich.edu>]

Steve French wrote:

  If that is the case (ie that cifs and nfs never need to set these over
  tcp - I am still having trouble reconciling that with the NFS guys'
  comments that they must set rcvbuf (and Jim's comment below)

If you have an application that wants to read a big chunk of data from a
socket, and won't remove any of that data from the socket until the entire
chunk has arrived, then the application must set the receive socket buffer
size big enough to hold the entire chunk.  Otherwise the application will
stall.

As far as I can tell, the corresponding situation does not hold for send
buffers, because the tcp layer will grow the send buffer to be big enough to
hold whatever the application wants to send.  But I don't know if that's
always true, or if there is some limit, so to be safe our NFS patch
continues to set both the receive and send buffer sizes.