On Tue, Sep 10, 2019 at 11:13:50AM +0100, Zapolski, MarcinX A wrote: > > -----Original Message----- > > From: Bruce Richardson [mailto:bruce.richard...@intel.com] > > Sent: Tuesday, September 10, 2019 12:07 PM > > To: Zapolski, MarcinX A <marcinx.a.zapol...@intel.com> > > Cc: dev@dpdk.org > > Subject: Re: [dpdk-dev] [RFC 19.11 v2 1/3] ethdev: hide key ethdev > > structures from public API > > > > On Tue, Sep 10, 2019 at 09:59:51AM +0000, Zapolski, MarcinX A wrote: > > > <...> > > > > @@ -3994,7 +4054,55 @@ void * > > > > rte_eth_dev_get_sec_ctx(uint16_t port_id); > > > > > > > > > > > > -#include <rte_ethdev_core.h> > > > > +struct rte_eth_dev_callback; > > > > +/** Structure to keep track of registered callbacks */ > > > > +TAILQ_HEAD(rte_eth_dev_cb_list, rte_eth_dev_callback); > > > > + > > > > +/** > > > > + * Structure used to hold information about the callbacks to be > > > > +called for a > > > > + * queue on RX and TX. > > > > + */ > > > > +struct rte_eth_rxtx_callback { > > > > + struct rte_eth_rxtx_callback *next; > > > > + union{ > > > > + rte_rx_callback_fn rx; > > > > + rte_tx_callback_fn tx; > > > > + } fn; > > > > + void *param; > > > > +}; > > > > + > > > > +/** > > > > + * The generic data structure associated with each ethernet device. > > > > + * > > > > + * Pointers to burst-oriented packet receive and transmit functions > > > > +are > > > > + * located at the beginning of the structure, along with the > > > > +pointer to > > > > + * where all the data elements for the particular device are stored > > > > +in shared > > > > + * memory. This split allows the function pointer and driver data > > > > +to be per- > > > > + * process, while the actual configuration data for the device is > > > > shared. > > > > + */ > > > I would like to raise one more concern (maybe not the smartest thing > > > to do involving my own patch, but I will sleep better when this is > > > resolved). > > > Does anyone know what the author of this comment had in mind? I could > > > not find any code that utilizes this split, and this patch clearly > > > breaks it. If it is obsolete, I guess this comment could be removed. > > > > As the comment suggest the split is for multi-process suport. The data > > structures for the RX/TX queues etc. all need to be common across > > processes, while the function pointers need to be per-process. Originally, > > in > > very early versions of DPDK there was no rte_eth_dev_data structure, all > > fields - both data and function pointers - were in rte_eth_dev itself. > > > > /Bruce > > Yes, I see the need to have the elements separated. But the comment suggests > that the order of variables in structure is important. I just want to make > sure that it is not.
I don't believe it's particularly significant. The main thing was to ensure that we kept the fast-path accessed data on the same cacheline.
