I found another issue while testing w.r.t vhostuser ports.
When non-pmd thread tries to send packets to vHostUser port below is the call
patch
dp_execute_cb()
netdev_dpdk_vhost_send() [(may_steal == true) and (Pkt src type ==
DPBUF_MALLOC)]
dpdk_do_tx_copy()
__netdev_dpdk_vhost_send() [ Pkts are queues till the
cnt reaches 32]
The packets aren't flushed and the ping can fail in this cases. To verify if
it works, I invoked 'vhost_tx_burst()' in dpdk_do_tx_copy().
But you mentioned this may pose a problem w.r.t flood traffic having higher
priority in other mail. What is the best place to flush the non-PMD thread
queues?
- Bhanuprakash.
>
>>At least, you have to flush non-PMD threads too.
>
>In case of non PMD threads we don’t have to flush as the packets aren't
>queued and bursted instantly. The call path on the transmit side is:
>
>Vswitchd thread:
>
> dp_execute_cb()
> netdev_send()
> netdev_dpdk_send__()
> dpdk_do_tx_copy()
> netdev_dpdk_eth_tx_burst(). [ Burst packets
> immediately]
>
>- Bhanuprakash.
>
>>
>>On 18.06.2017 22:56, Bhanuprakash Bodireddy wrote:
>>> Under low rate traffic conditions, there can be 2 issues.
>>> (1) Packets potentially can get stuck in the intermediate queue.
>>> (2) Latency of the packets can increase significantly due to
>>> buffering in intermediate queue.
>>>
>>> This commit handles the (1) issue by flushing the tx port queues from
>>> PMD processing loop. Also this commit addresses issue (2) by flushing
>>> the tx queues after every rxq port processing. This reduces the
>>> latency with out impacting the forwarding throughput.
>>>
>>> MASTER
>>> --------
>>> Pkt size min(ns) avg(ns) max(ns)
>>> 512 4,631 5,022 309,914
>>> 1024 5,545 5,749 104,294
>>> 1280 5,978 6,159 45,306
>>> 1518 6,419 6,774 946,850
>>>
>>> MASTER + COMMIT
>>> -----------------
>>> Pkt size min(ns) avg(ns) max(ns)
>>> 512 4,711 5,064 182,477
>>> 1024 5,601 5,888 701,654
>>> 1280 6,018 6,491 533,037
>>> 1518 6,467 6,734 312,471
>>>
>>> PMDs can be teared down and spawned at runtime and so the rxq and txq
>>> mapping of the PMD threads can change. In few cases packets can get
>>> stuck in the queue due to reconfiguration and this commit helps flush
>>> the queues.
>>>
>>> Suggested-by: Eelco Chaudron <echau...@redhat.com>
>>> Reported-at:
>>> https://mail.openvswitch.org/pipermail/ovs-dev/2017-April/331039.html
>>> Signed-off-by: Bhanuprakash Bodireddy
>>> <bhanuprakash.bodire...@intel.com>
>>> Signed-off-by: Antonio Fischetti <antonio.fische...@intel.com>
>>> Co-authored-by: Antonio Fischetti <antonio.fische...@intel.com>
>>> Signed-off-by: Markus Magnusson <markus.magnus...@ericsson.com>
>>> Co-authored-by: Markus Magnusson <markus.magnus...@ericsson.com>
>>> Acked-by: Eelco Chaudron <echau...@redhat.com>
>>> ---
>>> lib/dpif-netdev.c | 5 +++++
>>> 1 file changed, 5 insertions(+)
>>>
>>> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c index
>>> d59208e..dfd88aa 100644
>>> --- a/lib/dpif-netdev.c
>>> +++ b/lib/dpif-netdev.c
>>> @@ -3761,6 +3761,8 @@ reload:
>>> for (i = 0; i < poll_cnt; i++) {
>>> dp_netdev_process_rxq_port(pmd, poll_list[i].rx,
>>> poll_list[i].port_no);
>>> +
>>> + dp_netdev_flush_txq_ports(pmd);
>>> }
>>>
>>> if (lc++ > 1024) {
>>> @@ -3781,6 +3783,9 @@ reload:
>>> }
>>> }
>>>
>>> + /* Flush the queues as part of reconfiguration logic. */
>>> + dp_netdev_flush_txq_ports(pmd);
>>> +
>>> poll_cnt = pmd_load_queues_and_ports(pmd, &poll_list);
>>> exiting = latch_is_set(&pmd->exit_latch);
>>> /* Signal here to make sure the pmd finishes
>>>
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