Hi Billy, On Thu, 9 Mar 2017 15:51:17 -0500, Billy McFall <bmcf...@redhat.com> wrote: > Add a new API to force free consumed buffers on Tx ring. API will return > the number of packets freed (0-n) or error code if feature not supported > (-ENOTSUP) or input invalid (-ENODEV). > > Please double check my python coding in conf.py and make sure I > implemented 'feature_str_len' properly. > > Signed-off-by: Billy McFall <bmcf...@redhat.com>
[...] > diff --git a/doc/guides/prog_guide/mempool_lib.rst > b/doc/guides/prog_guide/mempool_lib.rst > index ffdc109..a117881 100644 > --- a/doc/guides/prog_guide/mempool_lib.rst > +++ b/doc/guides/prog_guide/mempool_lib.rst > @@ -132,6 +132,32 @@ These user-owned caches can be explicitly passed to > ``rte_mempool_generic_put()` > The ``rte_mempool_default_cache()`` call returns the default internal cache > if any. > In contrast to the default caches, user-owned caches can be used by non-EAL > threads too. > > +In addition to a core's local cache, many of the drivers don't release the > mbuf back to the mempool, or local cache, > +immediately after the packet has been transmitted. > +Instead, they leave the mbuf in their Tx ring and either perform a bulk > release when the ``tx_rs_thresh`` has been > +crossed or free the mbuf when a slot in the Tx ring is needed. > + > +An application can request the driver to release used mbufs with the > ``rte_eth_tx_done_cleanup()`` API. > +This API requests the driver to release mbufs that are no longer in use, > independent of whether or not the > +``tx_rs_thresh`` has been crossed. > +There are two scenarios when an application may want the mbuf released > immediately: > + > +* When a given packet needs to be sent to multiple destination interfaces > (either for Layer 2 flooding or Layer 3 > + multi-cast). > + One option is to make a copy of the packet or a copy of the header portion > that needs to be manipulated. > + A second option is to transmit the packet and then poll the > ``rte_eth_tx_done_cleanup()`` API until the reference > + count on the packet is decremented. > + Then the same packet can be transmitted to the next destination interface. > + > +* If an application is designed to make multiple runs, like a packet > generator, and one run has completed. > + The application may want to reset to a clean state. > + In this case, it may want to call the ``rte_eth_tx_done_cleanup()`` API to > request each destination interface it has > + been using to release all of its used mbufs. > + > +To determine if a driver supports this API, check for the *Free Tx mbuf on > demand* feature in the *Network Interface > +Controller Drivers* document. I'm not sure the mempool documentation is the proper place to document this API. I'll suggest to move it in ethdev documentation (poll_mode_drv.rst). You can keep a small paragraph in mempool lib, but keep in mind that mempool is not necessarily a pool of mbuf (it can be any kind of object). Thanks, Olivier
