[dpdk-dev] [PATCH v15 4/7] drivers/net: update Rx RSS hash offload capabilities

[Pavan Nikhilesh Bhagavatula]

>-----Original Message-----
>From: dev <dev-bounces at dpdk.org> On Behalf Of Thomas Monjalon
>Sent: Thursday, October 31, 2019 7:33 PM
>To: Pavan Nikhilesh Bhagavatula <pbhagavatula at marvell.com>
>Cc: dev at dpdk.org; ferruh.yigit at intel.com;
>arybchenko at solarflare.com; Jerin Jacob Kollanukkaran
><jerinj at marvell.com>; Ajit Khaparde <ajit.khaparde at broadcom.com>;
>Somnath Kotur <somnath.kotur at broadcom.com>; Rahul Lakkireddy
><rahul.lakkireddy at chelsio.com>; Hemant Agrawal
><hemant.agrawal at nxp.com>; Sachin Saxena
><sachin.saxena at nxp.com>; Wenzhuo Lu <wenzhuo.lu at intel.com>;
>John Daley <johndale at cisco.com>; Hyong Youb Kim
><hyonkim at cisco.com>; Qi Zhang <qi.z.zhang at intel.com>; Xiao Wang
><xiao.w.wang at intel.com>; Ziyang Xuan <xuanziyang2 at huawei.com>;
>Xiaoyun Wang <cloud.wangxiaoyun at huawei.com>; Guoyang Zhou
><zhouguoyang at huawei.com>; Beilei Xing <beilei.xing at intel.com>;
>Jingjing Wu <jingjing.wu at intel.com>; Qiming Yang
><qiming.yang at intel.com>; Konstantin Ananyev
><konstantin.ananyev at intel.com>; Shijith Thotton
><sthotton at marvell.com>; Srisivasubramanian Srinivasan
><srinivasan at marvell.com>; Matan Azrad <matan at mellanox.com>;
>Shahaf Shuler <shahafs at mellanox.com>; Viacheslav Ovsiienko
><viacheslavo at mellanox.com>; Stephen Hemminger
><sthemmin at microsoft.com>; K. Y. Srinivasan <kys at microsoft.com>;
>Haiyang Zhang <haiyangz at microsoft.com>; Alejandro Lucero
><alejandro.lucero at netronome.com>; Nithin Kumar Dabilpuram
><ndabilpuram at marvell.com>; Kiran Kumar Kokkilagadda
><kirankumark at marvell.com>; Rasesh Mody <rmody at marvell.com>;
>Shahed Shaikh <shshaikh at marvell.com>; Maciej Czekaj
><mczekaj at marvell.com>; Yong Wang <yongwang at vmware.com>
>Subject: Re: [dpdk-dev] [PATCH v15 4/7] drivers/net: update Rx RSS
>hash offload capabilities
>
>29/10/2019 16:37, pbhagavatula at marvell.com:
>> From: Pavan Nikhilesh <pbhagavatula at marvell.com>
>>
>> Add DEV_RX_OFFLOAD_RSS_HASH flag for all PMDs that support RSS
>hash
>> delivery.
>>
>> Signed-off-by: Pavan Nikhilesh <pbhagavatula at marvell.com>
>> Reviewed-by: Andrew Rybchenko <arybchenko at solarflare.com>
>> Reviewed-by: Hemant Agrawal <hemant.agrawal at nxp.com>
>> Acked-by: Jerin Jacob <jerinj at marvell.com>
>> Acked-by: Ajit Khaparde <ajit.khaparde at broadcom.com>
>> ---
>> +	if (!(dev->data->dev_conf.rxmode.offloads &
>DEV_RX_OFFLOAD_RSS_HASH))
>> +		dev->data->dev_conf.rxmode.offloads |=
>DEV_RX_OFFLOAD_RSS_HASH;
>
>Excuse me, I miss why you need a check before setting the bit.

Currently, none of the PMDs support disabling RSS_HASH (except octeontx2) since it involves 
adding an if check in Rx routine that might lead to perf impact.
So, we are implicitly enabling the offload for all the PMDs if an application decides to disable
RSS_HASH. In future if PMD maintainer decides to add this feature she/he can remove the check.

>