[ovs-dev] [PATCH 2/6] netdev-dpdk: Adapt the requested number of tx and rx queues.

Daniele Di Proietto diproiettod at vmware.com
Mon Mar 16 18:28:11 UTC 2015


> On 16 Mar 2015, at 15:21, Traynor, Kevin <kevin.traynor at intel.com> wrote:
> 
>> 
>> -----Original Message-----
>> From: dev [mailto:dev-bounces at openvswitch.org] On Behalf Of Daniele Di
>> Proietto
>> Sent: Thursday, March 12, 2015 6:05 PM
>> To: dev at openvswitch.org
>> Subject: [ovs-dev] [PATCH 2/6] netdev-dpdk: Adapt the requested number of tx
>> and rx queues.
>> 
>> This commit changes the semantics of 'netdev_set_multiq()' to allow OVS
>> DPDK to run on device with limited multi queue support.
> 
> This is great, because on a dual socket system with an 18 core Haswell and HT 
> enabled you could be looking for 72 tx queues.
> 
>> 
>> * If a netdev doesn't have the requested number of rxqs it can simply
>>  inform the datapath without failing.
>> * If a netdev doesn't have the requested number of txqs it should try
>>  to create as many as possible and use locking.
>> 
>> Signed-off-by: Daniele Di Proietto <diproiettod at vmware.com>
>> ---
>> lib/netdev-dpdk.c     | 94 +++++++++++++++++++++++++++++++------------------
>> --
>> lib/netdev-provider.h | 11 ++++++
>> lib/netdev.c          | 10 ++++++
>> vswitchd/vswitch.xml  |  2 +-
>> 4 files changed, 80 insertions(+), 37 deletions(-)
>> 
>> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
>> index 54bc318..2278377 100644
>> --- a/lib/netdev-dpdk.c
>> +++ b/lib/netdev-dpdk.c
> 
> [snip]
> 
>> @@ -656,8 +684,10 @@ netdev_dpdk_set_multiq(struct netdev *netdev_, unsigned
>> int n_txq,
>>     netdev->up.n_txq = n_txq;
>>     netdev->up.n_rxq = n_rxq;
>>     rte_free(netdev->tx_q);
>> -    netdev_dpdk_alloc_txq(netdev, n_txq);
>>     err = dpdk_eth_dev_init(netdev);
>> +    netdev_dpdk_alloc_txq(netdev, netdev->real_n_txq);
>> +
>> +    netdev->txq_needs_locking = netdev->real_n_txq != netdev->up.n_txq;
> 
> Probably no point in allocing here if you have been returned an error from 
> dpdk_eth_dev_init(). You could just skip to the mutex_unlocking
> 

I could add another goto label, but it would complicate the code a bit.
If you don’t have a strong opinion about this I would prefer leaving it as it is.

>> 
>>     ovs_mutex_unlock(&netdev->mutex);
>>     ovs_mutex_unlock(&dpdk_mutex);
>> @@ -921,12 +951,21 @@ netdev_dpdk_send__(struct netdev_dpdk *dev, int qid,
>> }
>> 
> 
> [snip]
> 
>> 
>> -#define NETDEV_DPDK_CLASS(NAME, INIT, CONSTRUCT, MULTIQ, SEND)      \
>> +#define NETDEV_DPDK_CLASS(NAME, INIT, CONSTRUCT)              \
>> {                                                             \
>>     NAME,                                                     \
>>     INIT,                       /* init */                    \
>> @@ -1429,9 +1455,9 @@ unlock_dpdk:
>>     NULL, /* push header */                                   \
>>     NULL, /* pop header */                                    \
>>     netdev_dpdk_get_numa_id,    /* get_numa_id */             \
>> -    MULTIQ,                     /* set_multiq */              \
>> +    netdev_dpdk_set_multiq,     /* set_multiq */              \
> 
> I don’t think the netdev_dpdk_set_multiq() is needed for dpdkr as at 
> present you can't change the number of q's for dpdkr. It doesn't do 
> any harm either. Is there a reason you put it in e.g. future proofing?

I wanted to minimise (when possible) the differences between dpdk and dpdkr.
Besides set_multiq for dpdkr stores the requested number of transmission queues
on netdev->n_txq, which can be shown via ovs-appctl dpctl/show -s 




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