Re: [dpdk-users] Freeing up Mbuf

[Anupam Kapoor]

On Thu, Dec 22, 2016 at 10:17 PM, Kumaraparameshwaran Rathnavel <
kr...@cloudsimple.com> wrote:

> In FreeBSD the user can actually specify the free routine for the mbuf
> when the transmit routine is called. Is this implemented in DPDK.


​currently, afaik, dpdk ​does not provide this functionality. basically,
there is no way to poll the tx-ring for consumed buffers. or to put it
another way, rte_eth_tx_burst doesn't synchronously transmit the packets.

​--
kind regards
anupam​


In the beginning was the lambda, and the lambda was with Emacs, and Emacs
was the lambda.

Re: [dpdk-users] Freeing up Mbuf

[Take Ceara]

Hi Param,

On Thu, Dec 22, 2016 at 5:47 PM, Kumaraparameshwaran Rathnavel
 wrote:
> Hi All,
>
> The mbuf implementation is similar to the Network Driver of the FreeBSD 
> Network Driver. In DPDK userspace driver it is the responsibility of the 
> rte_eth_dev implementation to free the memory buffer associated with a Queue 
> when descriptors reach below a threshold. In FreeBSD the user can actually 
> specify the free routine for the mbuf when the transmit routine is called. Is 
> this implemented in DPDK. I basically will give the data buffer of the 
> application layer that will be chained with the Transport Layer Headers and I 
> do not want to free up the routines always. Is this possible?

You can send a clone of the mbuf (see rte_pktmbuf_clone). Cloning the
mbuf will increase the refcount of the direct mbuf (that stores the
actual data). When the driver is done transmitting the clone it will
decrement the refcount and only free the direct mbuf if the refcount
is 0 (see rte_pktmbuf_free_seg and __rte_pktmbuf_prefree_seg).

However, you need to be careful if you plan to change the data stored
in the direct mbuf and make sure there are no more clones of the data
pending transmission.

>
> Thanking You,
> Param.

Regards,
Dumitru

[dpdk-users] Freeing up Mbuf

[Kumaraparameshwaran Rathnavel]

Hi All,

The mbuf implementation is similar to the Network Driver of the FreeBSD Network 
Driver. In DPDK userspace driver it is the responsibility of the rte_eth_dev 
implementation to free the memory buffer associated with a Queue when 
descriptors reach below a threshold. In FreeBSD the user can actually specify 
the free routine for the mbuf when the transmit routine is called. Is this 
implemented in DPDK. I basically will give the data buffer of the application 
layer that will be chained with the Transport Layer Headers and I do not want 
to free up the routines always. Is this possible?

Thanking You,
Param.