>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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