On Wed, Mar 15, 2017 at 6:29 AM, Olivier Matz <olivier.m...@6wind.com> wrote:
> 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). > > Not sure this API needs to be documented in multiple places. I'll move the content to the poll_mode_drv.rst file. > > Thanks, > Olivier > > Billy
