From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Monjalon <thomas@monjalon.net>
Subject: Re: [PATCH] ethdev: add lock-less txq capability flag
Date: Mon, 24 Apr 2017 14:34:59 +0200
Message-ID: <1937111.PEUejtoCqE@xps>
References: <20170421122223.24194-1-jerin.jacob@caviumnetworks.com>
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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
To: Jerin Jacob <jerin.jacob@caviumnetworks.com>
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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?

[...]
> --- 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.
I wonder whether "lock free" wording is confusing because
the locks are probably handled in HW.
I think the good wording is "offloaded multi-thread capability",
maybe with a naming like DEV_TX_OFFLOAD_MT.

Anyway we should reference this flag in rte_eth_tx_burst()
and give more details in doc/guides/prog_guide/poll_mode_drv.rst.

Should we wait a first hardware PoC to add this flag?
Candidate for 17.08?