tcp: Acknowledge everything if it looks like bulk traffic, not interactive

...instead of checking if the current sending buffer is less than
SNDBUF_SMALL, because this isn't simply an optimisation to coalesce
ACK segments: we rely on having enough data at once from the sender
to make the buffer grow by means of TCP buffer size tuning
implemented in the Linux kernel.

This is important if we're trying to maximise throughput, but not
desirable for interactive traffic, where we want to be transparent as
possible and avoid introducing unnecessary latency.

Use the tcpi_delivery_rate field reported by the Linux kernel, if
available, to calculate the current bandwidth-delay product: if it's
significantly smaller than the available sending buffer, conclude that
we're not bandwidth-bound and this is likely to be interactive
traffic, so acknowledge data only as it's acknowledged by the peer.

Conversely, if the bandwidth-delay product is comparable to the size
of the sending buffer (more than 5%), we're probably bandwidth-bound
or... bound to be: acknowledge everything in that case.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

0 files changed, 0 insertions, 0 deletions