From: Thomas Monjalon <thomas@monjalon.net>
To: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Cc: dev@dpdk.org, bruce.richardson@intel.com,
harry.van.haaren@intel.com, hemant.agrawal@nxp.com,
gage.eads@intel.com, nipun.gupta@nxp.com,
santosh.shukla@caviumnetworks.com
Subject: Re: [dpdk-dev] [PATCH] ethdev: add lock-less txq capability flag
Date: Wed, 05 Jul 2017 19:46:54 +0200 [thread overview]
Message-ID: <3952630.qNnCRMOujm@xps> (raw)
In-Reply-To: <20170427105934.GA4375@jerin>
27/04/2017 13:00, Jerin Jacob:
> -----Original Message-----
> > Date: Mon, 24 Apr 2017 14:34:59 +0200
> > From: Thomas Monjalon <thomas@monjalon.net>
> > To: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> > Cc: dev@dpdk.org, bruce.richardson@intel.com, harry.van.haaren@intel.com,
> > hemant.agrawal@nxp.com, gage.eads@intel.com, nipun.gupta@nxp.com,
> > santosh.shukla@caviumnetworks.com
> > Subject: Re: [dpdk-dev] [PATCH] ethdev: add lock-less txq capability flag
> >
> > 21/04/2017 14:22, Jerin Jacob:
> > > if this flag is advertised by a PMD, Multiple threads can
> > > invoke rte_eth_tx_burst() concurrently on the same tx queue
> > > without SW lock. This is an HW feature found in some NICs
> > > and useful in the following use cases if HW supports it.
> >
> > Which hardware supports it?
>
> Cavium OCTEONTX Packet transmission HW block(PKO).
>
> >
> > [...]
> > > --- a/lib/librte_ether/rte_ethdev.h
> > > +++ b/lib/librte_ether/rte_ethdev.h
> > > +#define DEV_TX_OFFLOAD_TXQ_MT_LOCKFREE 0x00004000
> > > +/**< Multiple threads can invoke rte_eth_tx_burst() concurrently on the
> > > same + * tx queue without SW lock.
> > > + */
> >
> > Why TXQ in the name? DEV_TX_OFFLOAD_MT_LOCKFREE would be enough.
>
> OK
>
> > I wonder whether "lock free" wording is confusing because
> > the locks are probably handled in HW.
>
> Yes. Another reason why it possible because HW is not using ring like scheme(head and tail pointers)
> for Tx. "lock free" wording is more from software perspective.
>
> > I think the good wording is "offloaded multi-thread capability",
> > maybe with a naming like DEV_TX_OFFLOAD_MT.
>
> I think SW lock free is the capability here.IMO, it better to reflect the
> capability in the name(DEV_TX_OFFLOAD_MT_LOCKFREE).
>
> >
> > Anyway we should reference this flag in rte_eth_tx_burst()
> > and give more details in doc/guides/prog_guide/poll_mode_drv.rst.
>
> OK. Will address in v2.
>
> >
> > Should we wait a first hardware PoC to add this flag?
>
> If we are in agreement for method expose this feature through capability
> flag then should we really need to wait for driver implementation to
> accept the patch? Thoughts ?
> This flag has impact on how we handle the even dev applications if HW support available.
> We are in the process of up-streaming OCTEONTX ethdev driver, but there
> are few thing like with external pool manager and eventdev integration
> needs to be sorted out cleanly before that.
>
> > Candidate for 17.08?
Any news of a v2?
next prev parent reply other threads:[~2017-07-05 17:46 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-21 12:22 Jerin Jacob
2017-04-24 12:34 ` Thomas Monjalon
2017-04-27 11:00 ` Jerin Jacob
2017-07-05 17:46 ` Thomas Monjalon [this message]
2017-07-06 6:00 ` Jerin Jacob
2017-07-06 6:21 ` [dpdk-dev] [PATCH v2] ethdev: introduce lock-free " Jerin Jacob
2017-07-08 16:08 ` Thomas Monjalon
2017-07-10 16:56 ` Jerin Jacob
2017-07-10 16:59 ` [dpdk-dev] [PATCH v3 ] " Jerin Jacob
2017-07-13 12:02 ` Hemant Agrawal
2017-07-18 13:43 ` Thomas Monjalon
2017-07-13 18:42 ` santosh
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