Here are some patches that prepare for improvements in ACK generation and
for the implementation of the slow-start part of the protocol:
(1) Stop storing the protocol header in the Tx socket buffers, but rather
generate it on the fly. This potentially saves a little space and
makes it easier to alter the header just before transmission (the
flags may get altered and the serial number has to be changed).
(2) Mask off the Tx buffer annotations and add a flag to record which ones
have already been resent.
(3) Track RTT on a per-peer basis for use in future changes. Tracepoints
are added to log this.
(4) Send PING ACKs in response to incoming calls to elicit a PING-RESPONSE
ACK from which RTT data can be calculated. The response also carries
other useful information.
(5) Expedite PING-RESPONSE ACK generation from sendmsg. If we're actively
using sendmsg, this allows us, under some circumstances, to avoid
having to rely on the background work item to run to generate this
This requires ktime_sub_ms() to be added.
(6) Set the REQUEST-ACK flag on some DATA packets to elicit ACK-REQUESTED
ACKs from which RTT data can be calculated.
(7) Limit the use of pings and ACK requests for RTT determination.
The patches can be found here also:
David Howells (9):
rxrpc: Don't store the rxrpc header in the Tx queue sk_buffs
rxrpc: Add re-sent Tx annotation
rxrpc: Add per-peer RTT tracker
rxrpc: Send pings to get RTT data
rxrpc: Expedite ping response transmission
rxrpc: Add ktime_sub_ms()
rxrpc: Obtain RTT data by requesting ACKs on DATA packets
rxrpc: Reduce the number of PING ACKs sent
rxrpc: Reduce the number of ACK-Requests sent
include/linux/ktime.h | 5 ++
include/trace/events/rxrpc.h | 61 ++++++++++++++++++++++
net/rxrpc/ar-internal.h | 47 ++++++++++++-----
net/rxrpc/call_event.c | 57 +++++++++++---------
net/rxrpc/conn_object.c | 1
net/rxrpc/input.c | 100 ++++++++++++++++++++++++++++++++++--
net/rxrpc/misc.c | 25 ++++++---
net/rxrpc/output.c | 117 ++++++++++++++++++++++++++++++++----------
net/rxrpc/peer_event.c | 39 ++++++++++++++
net/rxrpc/peer_object.c | 1
net/rxrpc/rxkad.c | 8 +--
net/rxrpc/sendmsg.c | 56 ++++----------------
net/rxrpc/sysctl.c | 2 -
13 files changed, 389 insertions(+), 130 deletions(-)