[CCID2]: Remove redundant ack-counting variable
The code used two different variables to count Acks, one of them redundant.
This patch reduces the number of Ack counters to one.
The type of the Ack counter has also been changed to u32 (twice the range of int);
and the variable has been renamed into `packets_acked' - for consistency with
RFC 3465 (and similarly named variables are used by TCP and SCTP).
Lastly, a slightly less aggressive `maxincr' increment is used (for even Ack Ratios,
maxincr was Ack Ratio/2 + 1 instead of Ack Ratio/2).
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
index 4f6c352..02d126d 100644
--- a/net/dccp/ccids/ccid2.c
+++ b/net/dccp/ccids/ccid2.c
@@ -199,9 +199,8 @@
hctx->ccid2hctx_pipe = 0;
/* clear state about stuff we sent */
- hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqh;
- hctx->ccid2hctx_ssacks = 0;
- hctx->ccid2hctx_acks = 0;
+ hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqh;
+ hctx->ccid2hctx_packets_acked = 0;
/* clear ack ratio state. */
hctx->ccid2hctx_rpseq = 0;
@@ -406,31 +405,15 @@
{
struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
- /* slow start */
if (hctx->ccid2hctx_cwnd < hctx->ccid2hctx_ssthresh) {
- hctx->ccid2hctx_acks = 0;
-
- /* We can increase cwnd at most maxincr [ack_ratio/2] */
- if (*maxincr) {
- /* increase every 2 acks */
- hctx->ccid2hctx_ssacks++;
- if (hctx->ccid2hctx_ssacks == 2) {
- hctx->ccid2hctx_cwnd++;
- hctx->ccid2hctx_ssacks = 0;
- *maxincr = *maxincr - 1;
- }
- } else {
- /* increased cwnd enough for this single ack */
- hctx->ccid2hctx_ssacks = 0;
+ if (*maxincr > 0 && ++hctx->ccid2hctx_packets_acked == 2) {
+ hctx->ccid2hctx_cwnd += 1;
+ *maxincr -= 1;
+ hctx->ccid2hctx_packets_acked = 0;
}
- } else {
- hctx->ccid2hctx_ssacks = 0;
- hctx->ccid2hctx_acks++;
-
- if (hctx->ccid2hctx_acks >= hctx->ccid2hctx_cwnd) {
- hctx->ccid2hctx_cwnd++;
- hctx->ccid2hctx_acks = 0;
- }
+ } else if (++hctx->ccid2hctx_packets_acked >= hctx->ccid2hctx_cwnd) {
+ hctx->ccid2hctx_cwnd += 1;
+ hctx->ccid2hctx_packets_acked = 0;
}
/* update RTO */
@@ -596,12 +579,13 @@
}
}
- /* If in slow-start, cwnd can increase at most Ack Ratio / 2 packets for
- * this single ack. I round up.
- * -sorbo.
+ /*
+ * In slow-start, cwnd can increase up to a maximum of Ack Ratio/2
+ * packets per acknowledgement. Rounding up avoids that cwnd is not
+ * advanced when Ack Ratio is 1 and gives a slight edge otherwise.
*/
- maxincr = dp->dccps_l_ack_ratio >> 1;
- maxincr++;
+ if (hctx->ccid2hctx_cwnd < hctx->ccid2hctx_ssthresh)
+ maxincr = DIV_ROUND_UP(dp->dccps_l_ack_ratio, 2);
/* go through all ack vectors */
while ((offset = ccid2_ackvector(sk, skb, offset,
