tipc: transfer broadcast nacks in link state messages
When we send broadcasts in clusters of more 70-80 nodes, we sometimes
see the broadcast link resetting because of an excessive number of
retransmissions. This is caused by a combination of two factors:
1) A 'NACK crunch", where loss of broadcast packets is discovered
and NACK'ed by several nodes simultaneously, leading to multiple
redundant broadcast retransmissions.
2) The fact that the NACKS as such also are sent as broadcast, leading
to excessive load and packet loss on the transmitting switch/bridge.
This commit deals with the latter problem, by moving sending of
broadcast nacks from the dedicated BCAST_PROTOCOL/NACK message type
to regular unicast LINK_PROTOCOL/STATE messages. We allocate 10 unused
bits in word 8 of the said message for this purpose, and introduce a
new capability bit, TIPC_BCAST_STATE_NACK in order to keep the change
backwards compatible.
Reviewed-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/tipc/msg.h b/net/tipc/msg.h
index 7cf52fb..c3832cd 100644
--- a/net/tipc/msg.h
+++ b/net/tipc/msg.h
@@ -719,6 +719,16 @@
return (char *)&m->hdr[TIPC_MEDIA_INFO_OFFSET];
}
+static inline u32 msg_bc_gap(struct tipc_msg *m)
+{
+ return msg_bits(m, 8, 0, 0x3ff);
+}
+
+static inline void msg_set_bc_gap(struct tipc_msg *m, u32 n)
+{
+ msg_set_bits(m, 8, 0, 0x3ff, n);
+}
+
/*
* Word 9
*/
