[dpdk-users] Freeing up Mbuf

Kumaraparameshwaran Rathnavel krath at cloudsimple.com
Sat Dec 24 05:53:34 CET 2016

Hi Dumitru,

Thankyou for the response. The rte_pktmbuf_clone routine allocates a new mbuf right?  I see that it allocated a newmbuf from the specified pool.

Thanking You,
> On 22-Dec-2016, at 10:30 PM, Take Ceara <dumitru.ceara at gmail.com> wrote:
> Hi Param,
> On Thu, Dec 22, 2016 at 5:47 PM, Kumaraparameshwaran Rathnavel
> <krath at cloudsimple.com> 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

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