rxrpc: Reduce the number of ACK-Requests sent
Reduce the number of ACK-Requests we set on DATA packets that we're sending
to reduce network traffic. We set the flag on odd-numbered DATA packets to
start off the RTT cache until we have at least three entries in it and then
probe once per second thereafter to keep it topped up.
This could be made tunable in future.
Note that from this point, the RXRPC_REQUEST_ACK flag is set on DATA
packets as we transmit them and not stored statically in the sk_buff.
Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
index db01fbb..282cb1e 100644
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -270,6 +270,12 @@
msg.msg_controllen = 0;
msg.msg_flags = 0;
+ /* If our RTT cache needs working on, request an ACK. */
+ if ((call->peer->rtt_usage < 3 && sp->hdr.seq & 1) ||
+ ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000),
+ ktime_get_real()))
+ whdr.flags |= RXRPC_REQUEST_ACK;
+
if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
static int lose;
if ((lose++ & 7) == 7) {
@@ -301,11 +307,14 @@
done:
if (ret >= 0) {
- skb->tstamp = ktime_get_real();
+ ktime_t now = ktime_get_real();
+ skb->tstamp = now;
smp_wmb();
sp->hdr.serial = serial;
- if (whdr.flags & RXRPC_REQUEST_ACK)
+ if (whdr.flags & RXRPC_REQUEST_ACK) {
+ call->peer->rtt_last_req = now;
trace_rxrpc_rtt_tx(call, rxrpc_rtt_tx_data, serial);
+ }
}
_leave(" = %d [%u]", ret, call->peer->maxdata);
return ret;