tipc: change socket buffer overflow control to respect sk_rcvbuf
As per feedback from the netdev community, we change the buffer
overflow protection algorithm in receiving sockets so that it
always respects the nominal upper limit set in sk_rcvbuf.
Instead of scaling up from a small sk_rcvbuf value, which leads to
violation of the configured sk_rcvbuf limit, we now calculate the
weighted per-message limit by scaling down from a much bigger value,
still in the same field, according to the importance priority of the
received message.
To allow for administrative tunability of the socket receive buffer
size, we create a tipc_rmem sysctl variable to allow the user to
configure an even bigger value via sysctl command. It is a size of
three (min/default/max) to be consistent with things like tcp_rmem.
By default, the value initialized in tipc_rmem[1] is equal to the
receive socket size needed by a TIPC_CRITICAL_IMPORTANCE message.
This value is also set as the default value of sk_rcvbuf.
Originally-by: Jon Maloy <jon.maloy@ericsson.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Jon Maloy <jon.maloy@ericsson.com>
[Ying: added sysctl variation to Jon's original patch]
Signed-off-by: Ying Xue <ying.xue@windriver.com>
[PG: don't compile sysctl.c if not config'd; add Documentation]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/Documentation/sysctl/net.txt b/Documentation/sysctl/net.txt
index 85ab72d..5369879 100644
--- a/Documentation/sysctl/net.txt
+++ b/Documentation/sysctl/net.txt
@@ -26,7 +26,7 @@
ipv4 IP version 4 x25 X.25 protocol
ipx IPX token-ring IBM token ring
bridge Bridging decnet DEC net
- ipv6 IP version 6
+ ipv6 IP version 6 tipc TIPC
..............................................................................
1. /proc/sys/net/core - Network core options
@@ -207,3 +207,18 @@
The /proc/net/ipx_route table holds a list of IPX routes. For each route it
gives the destination network, the router node (or Directly) and the network
address of the router (or Connected) for internal networks.
+
+6. TIPC
+-------------------------------------------------------
+
+The TIPC protocol now has a tunable for the receive memory, similar to the
+tcp_rmem - i.e. a vector of 3 INTEGERs: (min, default, max)
+
+ # cat /proc/sys/net/tipc/tipc_rmem
+ 4252725 34021800 68043600
+ #
+
+The max value is set to CONN_OVERLOAD_LIMIT, and the default and min values
+are scaled (shifted) versions of that same value. Note that the min value
+is not at this point in time used in any meaningful way, but the triplet is
+preserved in order to be consistent with things like tcp_rmem.