Re: [dpdk-dev] [PATCH v4] ethdev: check Rx/Tx offloads

["Zhang, Qi Z" <qi.z.zhang@intel.com>]

> -----Original Message-----
> From: Thomas Monjalon [mailto:thomas@monjalon.net]
> Sent: Thursday, April 26, 2018 4:19 PM
> To: Zhang, Qi Z <qi.z.zhang@intel.com>
> Cc: Yigit, Ferruh <ferruh.yigit@intel.com>; Dai, Wei <wei.dai@intel.com>;
> dev@dpdk.org
> Subject: Re: [PATCH v4] ethdev: check Rx/Tx offloads
> 
> 26/04/2018 09:59, Zhang, Qi Z:
> >
> > > -----Original Message-----
> > > From: Yigit, Ferruh
> > > Sent: Thursday, April 26, 2018 1:05 AM
> > > To: Dai, Wei <wei.dai@intel.com>; thomas@monjalon.net; Zhang, Qi Z
> > > <qi.z.zhang@intel.com>
> > > Cc: dev@dpdk.org
> > > Subject: Re: [PATCH v4] ethdev: check Rx/Tx offloads
> > >
> > > On 4/25/2018 12:50 PM, Wei Dai wrote:
> > > > This patch check if a requested offloading is supported in the
> > > > device capability.
> > > > Any offloading is disabled by default if it is not set in
> > > > rte_eth_dev_configure( ) and rte_eth_[rt]x_queue_setup().
> > > > A per port offloading can only be enabled in rte_eth_dev_configure().
> > > > If a per port offloading is sent to rte_eth_[rt]x_queue_setup( ),
> > > > return error.
> > > > Only per queue offloading can be sent to rte_eth_[rt]x_queue_setup( ).
> > > > A per queue offloading is enabled only if it is enabled in
> > > > rte_eth_dev_configure( ) OR if it is enabled in
> > > > rte_eth_[rt]x_queue_setup( ).
> > > > If a per queue offloading is enabled in rte_eth_dev_configure(),
> > > > it can't be disabled in rte_eth_[rt]x_queue_setup( ).
> > > > If a per queue offloading is disabled in rte_eth_dev_configure( ),
> > > > it can be enabled or disabled( ) in rte_eth_[rt]x_queue_setup( ).
> > > >
> > > > This patch can make such checking in a common way in rte_ethdev
> > > > layer to avoid same checking in underlying PMD.
> > >
> > > Hi Wei,
> > >
> > > For clarification, there is existing API for rc1, and there is a
> > > suggested update in API for rc2. I guess this patch is for suggested update
> in rc2?
> > >
> > > > Signed-off-by: Wei Dai <wei.dai@intel.com>
> > > >
> > > > ---
> > > > v4: fix a wrong description in git log message.
> > > >
> > > > v3: rework according to dicision of offloading API in community
> > > >
> > > > v2: add offloads checking in rte_eth_dev_configure( ).
> > > >     check if a requested offloading is supported.
> > > > ---
> > > >  lib/librte_ether/rte_ethdev.c | 76
> > > > +++++++++++++++++++++++++++++++++++++++++++
> > > >  1 file changed, 76 insertions(+)
> > > >
> > > > diff --git a/lib/librte_ether/rte_ethdev.c
> > > > b/lib/librte_ether/rte_ethdev.c index f0f53d4..70a7904 100644
> > > > --- a/lib/librte_ether/rte_ethdev.c
> > > > +++ b/lib/librte_ether/rte_ethdev.c
> > > > @@ -1196,6 +1196,28 @@ rte_eth_dev_configure(uint16_t port_id,
> > > uint16_t nb_rx_q, uint16_t nb_tx_q,
> > > >  							ETHER_MAX_LEN;
> > > >  	}
> > > >
> > > > +	/* Any requested offload must be within its device capability */
> > > > +	if ((local_conf.rxmode.offloads & dev_info.rx_offload_capa) !=
> > > > +	     local_conf.rxmode.offloads) {
> > > > +		RTE_PMD_DEBUG_TRACE("ethdev port_id=%d requested Rx
> > > offloads "
> > > > +				    "0x%" PRIx64 " doesn't match Rx offloads "
> > > > +				    "capability 0x%" PRIx64 "\n",
> > > > +				    port_id,
> > > > +				    local_conf.rxmode.offloads,
> > > > +				    dev_info.rx_offload_capa);
> > > > +		return -EINVAL;
> > > > +	}
> > > > +	if ((local_conf.txmode.offloads & dev_info.tx_offload_capa) !=
> > > > +	     local_conf.txmode.offloads) {
> > > > +		RTE_PMD_DEBUG_TRACE("ethdev port_id=%d requested Tx
> > > offloads "
> > > > +				    "0x%" PRIx64 " doesn't match Tx offloads "
> > > > +				    "capability 0x%" PRIx64 "\n",
> > > > +				    port_id,
> > > > +				    local_conf.txmode.offloads,
> > > > +				    dev_info.tx_offload_capa);
> > > > +		return -EINVAL;
> > > > +	}
> > > +1 having these checks here.
> > >
> > > > +
> > > >  	/*
> > > >  	 * Setup new number of RX/TX queues and reconfigure device.
> > > >  	 */
> > > > @@ -1547,6 +1569,33 @@ rte_eth_rx_queue_setup(uint16_t port_id,
> > > uint16_t rx_queue_id,
> > > >  						    &local_conf.offloads);
> > > >  	}
> > > >
> > > > +	/*
> > > > +	 * Only per-queue offload can be enabled from application.
> > > > +	 * If any pure per-port offload is sent to this function, return
> -EINVAL
> > > > +	 */
> > > > +	if ((local_conf.offloads & dev_info.rx_queue_offload_capa) !=
> > > > +	     local_conf.offloads) {
> > > > +		RTE_PMD_DEBUG_TRACE("Ethdev port_id=%d
> rx_queue_id=%d "
> > > > +				    "Requested offload 0x%" PRIx64 "doesn't "
> > > > +				    "match per-queue capability 0x%" PRIx64
> > > > +				    " in rte_eth_rx_queue_setup( )\n",
> > > > +				    port_id,
> > > > +				    rx_queue_id,
> > > > +				    local_conf.offloads,
> > > > +				    dev_info.rx_queue_offload_capa);
> > > > +		return -EINVAL;
> > > > +	}
> > >
> > > There is a change here. If requested offload is already enabled in
> > > port level, instead of returning error, ignore it.
> > > So this removes the restriction for apps that "only an offload from
> > > queue capabilities can be send for queue_setup() functions". This is
> > > not requirement for application as it has been before, but this is
> > > allowed for app now.
> > >
> > > If app tried to enable a port offload in queue level that is not
> > > already enabled, it should still return error.
> > >
> > > > +
> > > > +	/*
> > > > +	 * If a per-queue offload is enabled in rte_eth_dev_configure( ),
> > > > +	 * it is also enabled on all queues and can't be disabled here.
> > > > +	 * If it is diabled in rte_eth_dev_configure( ), it can be enabled
> > > > +	 * or disabled here.
> > > > +	 * If a per-port offload is enabled in rte_eth_dev_configure( ),
> > > > +	 * it is also enabled for all queues here.
> > > > +	 */
> > > > +	local_conf.offloads |= dev->data->dev_conf.rxmode.offloads;
> > >
> > > I didn't get this one, why add rxmode.offloads into queue offloads?
> > >
> > > Based on above change Thomas has an suggestion [1]:
> > >
> > > "
> > > In the case of offload already enabled at port level and repeated in
> > > queue setup, ethdev can avoid passing it to the PMD queue setup
> function.
> > > "
> > >
> > > So almost reverse of what you are doing, strip rxmode.offloads from
> > > local_conf.offloads for PMDs. What do you think?
> >
> > Should we do like below
> > 	local_conf.offloads |= dev->data->dev_conf.rxmode.offloads;
> > 	local_conf.offloads &= dev_info.rx_queue_offload_capa
> >
> > I thinks it's better to only strip port offloads. But keep all queue
> > offload,  since this is exact we going to configure the queue and
> > during device start, it can simply iterate on each bit on local_conf.offloads
> to turn on queue offload and don't need to worry about rxmode.offloads.
> 
> No
> The offloads which are already enabled at port level does not need to be
> enabled again at queue level.
> But the PMD can decide to not configure the offload at port level for real,
> and configure the port offloads in every queue setups.
> It is an implementation choice, and can be different per-offload.

OK, got your point, that make sense.

> So it is simpler to filter such request for queue setups.
> This way, we will be sure that all offloads, requested in queue setup PMD
> function, must be setup for the queue.
> The PMD implementation will need to setup all the requested offloads in
> queue setup, plus the port offloads which were deferred to all queues.
> 
> Hope it's clear.
> 
>