On Fri, Oct 28, 2011 at 2:14 PM, Daniel Baluta [off-list ref] wrote:

RFC2581 ($4.2) specifies when an ACK should be generated as follows:

" .. an ACK SHOULD be generated for at least every second
 full-sized segment, and MUST be generated within 500 ms
 of the arrival of the first unacknowledged packet.
"

We export the number of segments and the timeout limits
specified above, so that a user can tune them according
to its needs.

Specifically:
       * /proc/sys/net/ipv4/tcp_delack_segs, represents
       the threshold for the number of segments.
       * /proc/sys/net/ipv4/tcp_delack_min, specifies
       the minimum timeout value
       * /proc/sys/net/ipv4/tcp_delack_max, specifies
       the maximum timeout value.

This is neat, but IMO it should be per socket -- I (and possibly most
other people who would use it) want to do this kind of tuning per
flow, not per-route or per-interface.

--Andy