Re: Survey for final decision about per-port offload API

From: Olivier Matz <olivier.matz@6wind.com>
To: Thomas Monjalon <thomas@monjalon.net>
Cc: dev@dpdk.org, Ajit Khaparde <ajit.khaparde@broadcom.com>,
	Jerin Jacob <jerin.jacob@caviumnetworks.com>,
	Shijith Thotton <shijith.thotton@cavium.com>,
	Santosh Shukla <santosh.shukla@caviumnetworks.com>,
	Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>,
	John Daley <johndale@cisco.com>,
	Wenzhuo Lu <wenzhuo.lu@intel.com>,
	Konstantin Ananyev <konstantin.ananyev@intel.com>,
	Beilei Xing <beilei.xing@intel.com>,
	Qi Zhang <qi.z.zhang@intel.com>,
	Jingjing Wu <jingjing.wu@intel.com>,
	Adrien Mazarguil <adrien.mazarguil@6wind.com>,
	Nelio Laranjeiro <nelio.laranjeiro@6wind.com>,
	Yongseok Koh <yskoh@mellanox.com>,
	Shahaf Shuler <shahafs@mellanox.com>,
	Tomasz Duszynski <tdu@semihalf.com>,
	Jianbo Liu <jianbo.liu@arm.com>,
	Alejandro Lucero <alejandro.lucero@netronome.com>,
	Hemant Agrawal <hemant.agrawal@nxp.com>,
	Shreyansh Jain <shreyansh.jain@nxp.com>,
	Harish Patil <harish.patil@cavium
Subject: Re: Survey for final decision about per-port offload API
Date: Wed, 11 Apr 2018 16:42:42 +0200	[thread overview]
Message-ID: <20180411144242.rkiavbycil3drwc2@platinum> (raw)
In-Reply-To: <2759953.P7QpFFSjiU@xps>

On Fri, Mar 30, 2018 at 03:47:55PM +0200, Thomas Monjalon wrote:
> There are some discussions about a specific part of the offload API:
> 	"To enable per-port offload, the offload should be set on both
> 	device configuration and queue setup."
> 
> It means the application must repeat the port offload flags
> in rte_eth_conf.[rt]xmode.offloads and rte_eth_[rt]xconf.offloads,
> when calling respectively rte_eth_dev_configure() and
> rte_eth_[rt]x_queue_setup for each queue.
> 
> The PMD must check if there is mismatch, i.e. a port offload not
> repeated in queue setup.
> There is a proposal to do this check at ethdev level:
> 	http://dpdk.org/ml/archives/dev/2018-March/094023.html
> 
> It was also proposed to relax the API and allow "forgetting" port
> offloads in queue offloads:
> 	http://dpdk.org/ml/archives/dev/2018-March/092978.html
> 
> It would mean the offloads applied to a queue result of OR operation:
> 	rte_eth_conf.[rt]xmode.offloads | rte_eth_[rt]xconf.offloads
> 
> 1/ Do you agree with above API change?

yes

> If we agree with this change, we need to update the documentation
> and remove the checks in PMDs.
> Note: no matter what is decided here, 18.05-rc1 should have all PMDs
> switched to the API which was defined in 17.11.
> Given that API is new and not yet adopted by the applications,
> the sonner it is fixed, the better.
> 
> 2/ Should we do this change in 18.05-rc2?

yes

> At the same time, we want to make clear that an offload enabled at
> port level, cannot be disabled at queue level.
> 
> 3/ Do you agree with above statement (to be added in the doc)?

yes

> There is the same kind of confusion in the offload capabilities:
> 	rte_eth_dev_info.[rt]x_offload_capa
> 	rte_eth_dev_info.[rt]x_queue_offload_capa
> The queue capabilities must be a subset of port capabilities,
> i.e. every queue capabilities must be reported as port capabilities.
> But the port capabilities should be reported at queue level
> only if it can be applied to a specific queue.
> 
> 4/ Do you agree with above statement (to be added in the doc)?

yes