[ovs-dev] [PATCH v2] netdev-dpdk: Use different constant for ring size

[Pravin Shelar]

On Wed, Aug 6, 2014 at 6:07 PM, Daniele Di Proietto
<ddiproietto at vmware.com> wrote:
>
>
> On 8/6/14, 3:30 PM, "Pravin Shelar" <pshelar at nicira.com> wrote:
>
>>On Wed, Jul 30, 2014 at 8:51 AM, Daniele Di Proietto
>><ddiproietto at vmware.com> wrote:
>>> DPDK rings must have a power-of-two size.
>>>
>>> Signed-off-by: Daniele Di Proietto <ddiproietto at vmware.com>
>>> ---
>>>  lib/netdev-dpdk.c | 6 ++++--
>>>  1 file changed, 4 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
>>> index b45e367..a779833 100644
>>> --- a/lib/netdev-dpdk.c
>>> +++ b/lib/netdev-dpdk.c
>>> @@ -125,6 +125,8 @@ static const struct rte_eth_txconf tx_conf = {
>>>
>>>  enum { MAX_RX_QUEUE_LEN = 192 };
>>>  enum { MAX_TX_QUEUE_LEN = 384 };
>>Is there any benefit of keeping separate RX and TX QUEUE size ?
>
> This patch just fixes a bug related to DPDK rings.
>
> The TX queue is bigger because in a single PMD thread iteration multiple
> NICs _could_ receive a whole batch of packets that has to be sent to the
> same output NIC. Having a bigger TX queue size reduces the calls to
> dpdk_queue_flush__().
>
> I¹m not sure in practice how much this would affect performance, but I do
> not see any harm in keeping them separate.
>
> Anyway, if you think we should merge them, I trust your judgement!
>

OK, I pushed the patch.