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rxrpc: Obtain RTT data by requesting ACKs on DATA packets

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In addition to sending a PING ACK to gain RTT data, we can set the
RXRPC_REQUEST_ACK flag on a DATA packet and get a REQUESTED-ACK ACK.  The
ACK packet contains the serial number of the packet it is in response to,
so we can look through the Tx buffer for a matching DATA packet.

This requires that the data packets be stamped with the time of
transmission as a ktime rather than having the resend_at time in jiffies.

This further requires the resend code to do the resend determination in
ktimes and convert to jiffies to set the timer.

Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells
2016-09-22 00:29:31 +01:00
parent 77f2efcbdd
commit 50235c4b5a
7 changed files with 57 additions and 20 deletions
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7
net/rxrpc/output.c
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@@ -300,9 +300,12 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct sk_buff *skb)
goto send_fragmentable;
done:
if (ret == 0) {
sp->resend_at = jiffies + rxrpc_resend_timeout;
if (ret >= 0) {
skb->tstamp = ktime_get_real();
smp_wmb();
sp->hdr.serial = serial;
if (whdr.flags & RXRPC_REQUEST_ACK)
trace_rxrpc_rtt_tx(call, rxrpc_rtt_tx_data, serial);
}
_leave(" = %d [%u]", ret, call->peer->maxdata);
return ret;