Re: [dpdk-dev] [PATCH v4 1/4] ethdev: add the API for getting burst mode information

["Wang, Haiyue" <haiyue.wang@intel.com>]

> -----Original Message-----
> From: Yigit, Ferruh <ferruh.yigit@intel.com>
> Sent: Thursday, October 31, 2019 22:58
> To: Wang, Haiyue <haiyue.wang@intel.com>; Jerin Jacob <jerinjacobk@gmail.com>
> Cc: Thomas Monjalon <thomas@monjalon.net>; dpdk-dev <dev@dpdk.org>; Ye, Xiaolong
> <xiaolong.ye@intel.com>; Kinsella, Ray <ray.kinsella@intel.com>; Iremonger, Bernard
> <bernard.iremonger@intel.com>; Sun, Chenmin <chenmin.sun@intel.com>; Andrew Rybchenko
> <arybchenko@solarflare.com>; Slava Ovsiienko <viacheslavo@mellanox.com>; Stephen Hemminger
> <stephen@networkplumber.org>; David Marchand <david.marchand@redhat.com>; Jerin Jacob
> <jerinj@marvell.com>
> Subject: Re: [dpdk-dev] [PATCH v4 1/4] ethdev: add the API for getting burst mode information
> 
> On 10/31/2019 11:16 AM, Wang, Haiyue wrote:
> >> -----Original Message-----
> >> From: Jerin Jacob <jerinjacobk@gmail.com>
> >> Sent: Thursday, October 31, 2019 18:46
> >> To: Wang, Haiyue <haiyue.wang@intel.com>
> >> Cc: Yigit, Ferruh <ferruh.yigit@intel.com>; Thomas Monjalon <thomas@monjalon.net>; dpdk-dev
> >> <dev@dpdk.org>; Ye, Xiaolong <xiaolong.ye@intel.com>; Kinsella, Ray <ray.kinsella@intel.com>;
> >> Iremonger, Bernard <bernard.iremonger@intel.com>; Sun, Chenmin <chenmin.sun@intel.com>; Andrew
> >> Rybchenko <arybchenko@solarflare.com>; Slava Ovsiienko <viacheslavo@mellanox.com>; Stephen
> Hemminger
> >> <stephen@networkplumber.org>; David Marchand <david.marchand@redhat.com>; Jerin Jacob
> >> <jerinj@marvell.com>
> >> Subject: Re: [dpdk-dev] [PATCH v4 1/4] ethdev: add the API for getting burst mode information
> >>
> >>>> 'rte_eth_burst_mode_option_name()' can get "struct rte_eth_burst_mode" as
> >>>> parameter and convert the 'options' to string and combine into single string as
> >>>> a helper function to the applications.
> >>>>
> >>>
> >>> Change:
> >>> const char *
> >>> rte_eth_burst_mode_option_name(uint64_t option)
> >>>
> >>> to:
> >>> int
> >>> rte_eth_burst_mode_option_name(struct rte_eth_burst_mode *mode, char *str) ?
> >>
> >>
> >> Since we are not ready to _remove_ flags in public API and rc2 time is
> >> ticking, probably the following the change
> >> would be enough. IMO, This API can be used only for logging purpose, I
> >> don't want to spend too
> >> many cycles on this discussion. I am leaving the decision to ethdev
> >> maintainers to accommodate
> >> the specifics of adding a string-based alternate options scheme.
> >>
> >
> > Thanks, Jerin.
> >
> >>
> >> [master][dpdk.org] $ git diff
> >> diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h
> >> index c36c1b631..2f9d2c0a7 100644
> >> --- a/lib/librte_ethdev/rte_ethdev.h
> >> +++ b/lib/librte_ethdev/rte_ethdev.h
> >> @@ -1272,8 +1272,11 @@ enum rte_eth_burst_mode_option {
> >>   * Ethernet device RX/TX queue packet burst mode information structure.
> >>   * Used to retrieve information about packet burst mode setting.
> >>   */
> >> +#define RTE_ETH_BURST_MODE_ALT_OPT_SIZE 128
> 
> Should we make it bigger to prevent ABI break just because of this later? Like
> 512 or bigger?
> 

Use 1024 ?

> >> +
> >>  struct rte_eth_burst_mode {
> >>         uint64_t options;
> >> +       char alternate_options[RTE_ETH_BURST_MODE_ALT_OPT_SIZE];
> >>  };
> >
> > +1
> >
> 
> +1
> 
> It is not as flexible as getting the size from the PMD but much simpler, both
> for the user and PMD.
> 
> And what about dropping the 'rte_eth_burst_mode_option_name()', if
> 'rte_eth_tx_burst_mode_get()' converts the 'options' to text
> ('alternate_options') as Jerin suggested, we can drop it.
> 
> So only difference from what Jerin suggested will be keeping 'uint64_t options'
> public for known/limited standardized options, which is currently only for
> vectorization information.

Since 'struct rte_eth_burst_mode' will be public, how about keep current design for
rte_eth_rx/tx_burst_mode_get() ?

But change 'const char *rte_eth_burst_mode_option_name(uint64_t option)' to
'int rte_eth_burst_mode_name(struct rte_eth_burst_mode *mode, char *name)' ?
When 'name' is NULL, return the buffer size will be used. If non-NULL, format
all the options. This will reduce the twice PMDs calls: 
	dev->dev_ops->rx/tx_burst_mode_get
And leave the filled *mode for application.