[tipc-discussion] "sendto" return EAGAIN in inter-node

[Marella P-G. <ph...@mo...>]

Hi all,=20

We are observing that the "sendto()" call in TIPC's Hello-World
application always returns EAGAIN after a set of messaging-stress tests.
This continues to happen well after the stress conditions are withdrawn.


Setup:=20

Node1: PowerPC, Linux Kernel=3D 2.6.9,=20
Node2: Dual Xeon (SMP), Linux Kernel=3D 2.6.9,=20
TIPC =3D 1.5.08=20
Communication medium =3D Gigabit Ethernet

Sequence leading to problem:

The two nodes are brought up and TIPC communication is established. A
few (~ 5-6) applications that use TIPC "lightly" are brought up on both
nodes. Finally, a test-application that performs several different
things (like different message-sizes, multiple subscriptions and
inter-node message communication) is continuously spawned and killed on
Node 2. The number of subscriptions/bindings never exceed 100 per node.
After a few iterations, the test-application blocks on the very first
"sendto()" call.=20

Some observations:

1) Only inter-node "sendto()" returns EAGAIN.=20
2) Except for messaging-speed, other system/TIPC resources are not
stressed.
3) All communication is connection-less (SOCK_RDM) as in Hello-World
4) Once the problem occurs on Node2, the "RX nacks" count on Node2 keeps
on increasing.  (see below for a dump)

We need help with this problem. With TIPC 1.4.01 this problem is not
seen. We would like to know any further information we could supply to
help solve this problem.=20

Thanks,
Phani Marella



PS: Output of tipc-config command after the problem sets in.=20
Link <1.1.8:eth0-1.1.1:eth0>
  ACTIVE  MTU:1500  Priority:10  Tolerance:1500 ms  Window:50 packets
  RX packets:88 fragments:2/1 bundles:0/0
  TX packets:2667 fragments:0/0 bundles:826/19803
  TX profile sample:1420 packets  average:60 octets
  0-64:98% -256:1% -1024:0% -4096:0% -16354:0% -32768:0% -66000:0%
  RX states:9337 probes:4443 naks:1327 defs:0 dups:0
  TX states:8883 probes:4440 naks:0 acks:0 dups:0
  Congestion bearer:0 link:1981  Send queue max:876 avg:71