Hi,
I may found a bug in ordered queues, but it seems to be so trivial that
I must think that I'm the one doing something wrong. The simplest way to
reproduce:
Take odp_pktio, and change ODP_SCHED_SYNC_ATOMIC to
ODP_SCHED_SYNC_ORDERED. Now, start it using at least two threads and in
scheduled mode (-c 2 -m 2), and sometimes the traffic stops after some
hundred packets. Although, I was able reproduce the phenomenon with 2
threads and 400mbps, the more threads and the higher bitrate gives you
the better chance to see it stopped. 12 threads and 30Gbps (40Gbps
interface, but pktgen can send only 30 with small packets) is almost
always enough.
Looking into the code with gdb, it seems that packets are received, but
queue_pktout_enq() puts the packets into a linked list (for reordering),
and it is waiting for the in-order packet which never arrives. I don't
know if that is lost, or was never received... I tried to set a
breakpoint to odp_packet_free() and to rte_pktmbuf_free(), but neither
one was called. Another interesting thing is that if packet forwarding
starts successfully (i.e. some thousand packets were forwarded), the
traffic never stops. Is this a bug, or just changing
ODP_SCHED_SYNC_ATOMIC to ODP_SCHED_SYNC_ORDERED is not enough, and
something is missing?
Thanks,
Gabor
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