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From: Jakub Kicinski <kubakici@wp.pl>
To: John Fastabend <john.fastabend@gmail.com>
Cc: Jakub Kicinski <jakub.kicinski@netronome.com>,
	"Samudrala, Sridhar" <sridhar.samudrala@intel.com>,
	Jiri Benc <jbenc@redhat.com>, Jiri Pirko <jiri@resnulli.us>,
	netdev@vger.kernel.org, Thomas Graf <tgraf@suug.ch>,
	Roopa Prabhu <roopa@cumulusnetworks.com>,
	ogerlitz@mellanox.com, ast@kernel.org, daniel@iogearbox.net,
	simon.horman@netronome.com, Paolo Abeni <pabeni@redhat.com>,
	Pravin B Shelar <pshelar@nicira.com>,
	hannes@stressinduktion.org
Subject: Re: [RFC] net: store port/representative id in metadata_dst
Date: Fri, 23 Sep 2016 21:45:44 +0100	[thread overview]
Message-ID: <20160923214544.6a3cd0ff@laptop> (raw)
In-Reply-To: <57E58FA6.3050001@gmail.com>

On Fri, 23 Sep 2016 13:25:10 -0700, John Fastabend wrote:
> On 16-09-23 01:17 PM, Jakub Kicinski wrote:
> > On Fri, 23 Sep 2016 10:22:59 -0700, Samudrala, Sridhar wrote:  
> >> On 9/23/2016 8:29 AM, Jakub Kicinski wrote:  
>  [...]  
>  [...]  
> >>
> >> The 'accel' parameter in dev_queue_xmit_accel() is currently only passed
> >> to ndo_select_queue() via netdev_pick_tx() and is used to select the tx 
> >> queue.
> >> Also, it is not passed all the way to the driver specific xmit routine.  
> >> Doesn't it require
> >> changing all the driver xmit routines if we want to pass this parameter?
> >>  
>  [...]  
> >>
> >> Yes.  The VFPR netdevs don't have any HW queues associated with them and 
> >> we would like
> >> to use the PF queues for the xmit.
> >> I was also looking into some way of passing the port id via skb 
> >> parameter to the
> >> dev_queue_xmit() call so that the PF xmit routine can do a directed 
> >> transmit to a specifc VF.
> >> Is skb->cb an option to pass this info?
> >> dst_metadata approach would work  too if it is acceptable.  
> > 
> > I don't think we can trust skb->cb to be set to anything meaningful
> > when the skb is received by the lower device. 
> 
> Agreed. I wouldn't recommend using skb->cb. How about passing it through
> dev_queue_xmit_accel() through to the driver?
> 
> If you pass the metadata through the dev_queue_xmit_accel() handle tx
> queue  selection would work using normal mechanisms (xps, select_queue,
> cls  hook, etc.). If you wanted to pick some specific queue based on
> policy the policy could be loaded into one of those hooks.

Do you mean without extending how accel is handled by
dev_queue_xmit_accel() today?  If my goal is to not have extra HW
queues then I don't see how I could mux in the lower dev without extra
locking (as I tried to explain two emails ago).  Sorry for being slow
here :(

  reply	other threads:[~2016-09-23 20:45 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-22 19:26 [RFC] net: store port/representative id in metadata_dst Jakub Kicinski
2016-09-23  6:34 ` Jiri Pirko
2016-09-23  9:06   ` Jiri Benc
2016-09-23 12:55     ` Jakub Kicinski
2016-09-23 14:23       ` John Fastabend
2016-09-23 15:29         ` Jakub Kicinski
2016-09-23 17:22           ` Samudrala, Sridhar
2016-09-23 20:17             ` Jakub Kicinski
2016-09-23 20:25               ` John Fastabend
2016-09-23 20:45                 ` Jakub Kicinski [this message]
2016-09-23 21:20                   ` John Fastabend
2016-09-29 11:10                     ` Jakub Kicinski

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