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Date: Tue, 26 Jan 2016 12:18:58 -0800
From: Bruce Richardson <bruce.richardson@intel.com>
To: Saurabh Mishra <saurabh.globe@gmail.com>
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Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] DPDK mbuf pool in SR-IOV env and one RX/TX queue
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On Mon, Jan 25, 2016 at 04:15:28PM -0800, Saurabh Mishra wrote:
> Hi Bruce --
> 
> >The sharing of the mbuf pool is not an issue, but sharing of rx/tx queues
> is.
> >The ethdev queues are not multi-thread safe, so to share a queue between
> processes
> >or threads, you need to put in locks or other access control mechanisms.
> [This
> >also implies a performance hit due to the locking]
> >Regards,
> >/Bruce
> 
> Right. So now we have only one process to do rx/tx on queue 0 if we detect
> that max queue support is 1.
> 
> However, we have noticed that if our process, which does rx/tx, is not
> primary, then we can't transmit the packet out with SR-IOV.
> 
> Is there any specific limitation on SR-IOV (the vf driver in dpdk) that
> only primary process should receive and transmit packets?
> 
> In our model, we have an agent process which monitor links and another
> process which does packet processing. If we make our agent process as
> primary then our secondary process is not able to send the packets --
> rte_eth_tx_burst() succeed but recipient does not receive the packet.
> 
> Thanks,
> /Saurabh

There should be no restrictions on RX/TX from secondary processes.

/Bruce