[dpdk-dev] [RFC] ethdev: support symmetric hash function

[Zhang, Qi Z]

> -----Original Message-----
> From: Adrien Mazarguil [mailto:adrien.mazarguil at 6wind.com]
> Sent: Thursday, July 4, 2019 5:07 PM
> To: Su, Simei <simei.su at intel.com>
> Cc: Zhang, Qi Z <qi.z.zhang at intel.com>; Wu, Jingjing <jingjing.wu at intel.com>;
> Xing, Beilei <beilei.xing at intel.com>; Yang, Qiming <qiming.yang at intel.com>;
> dev at dpdk.org; Shahaf Shuler <shahafs at mellanox.com>; Yongseok Koh
> <yskoh at mellanox.com>
> Subject: Re: [dpdk-dev] [RFC] ethdev: support symmetric hash function
> 
> On Thu, Jul 04, 2019 at 12:46:07PM +0800, simei wrote:
> > From: Simei Su <simei.su at intel.com>
> >
> > Currently, there are DEFAULT,TOEPLITZ and SIMPLE_XOR hash funtion.
> > To support symmetric hash by rte_flow RSS action, this RFC introduces
> > SYMMETRIC_TOEPLITZ to rte_eth_hash_function.
> >
> > Signed-off-by: Simei Su <simei.su at intel.com>
> > ---
> >  lib/librte_ethdev/rte_flow.h | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/lib/librte_ethdev/rte_flow.h
> > b/lib/librte_ethdev/rte_flow.h index f3a8fb1..e3c4fe5 100644
> > --- a/lib/librte_ethdev/rte_flow.h
> > +++ b/lib/librte_ethdev/rte_flow.h
> > @@ -1744,6 +1744,7 @@ enum rte_eth_hash_function {
> >  	RTE_ETH_HASH_FUNCTION_DEFAULT = 0,
> >  	RTE_ETH_HASH_FUNCTION_TOEPLITZ, /**< Toeplitz */
> >  	RTE_ETH_HASH_FUNCTION_SIMPLE_XOR, /**< Simple XOR */
> > +	RTE_ETH_HASH_FUNCTION_SYMMETRIC_TOEPLITZ, /**< Symmetric
> TOEPLITZ */
> 
> "Symmetric TOEPLITZ" => "Symmetric Toeplitz."
> 
> >  	RTE_ETH_HASH_FUNCTION_MAX,
> >  };
> 
> Other than that, no problem with this change (no ABI impact, no need for
> deprecation). Please update testpmd a part of the same patch:

Is it still ABI break but just with little risk? 
RTE_ETH_HASH_FUNCTION_MAX's value is changed anyway.
Should we just remove it, if no one use it?

Regards
Qi
> 
> - Wherever "toeplitz" is mentioned in test-pmd/cmdline.c.
> 
> - Ditto for flow command, i.e. add ACTION_RSS_FUNC_SYMMETRIC_TOEPLITZ
> to
>   test-pmd/cmdline_flow.c.
> 
> - Update "set_hash_global_config" documentation section in
>   testpmd_app_ug/testpmd_funcs.rst.
> 
> Note to Shahaf/Yongseok, since mlx5 supports both but defaults to symmetric
> Toeplitz on vanilla Linux and standard Toeplitz when using OFED, how about
> using this chance to make the algorithm configurable as well?
> 
> Thanks.
> 
> --
> Adrien Mazarguil
> 6WIND