Re: [dpdk-dev] [PATCH v2 05/39] examples/l3fwd: move to ethdev offloads API

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

-----Original Message-----
> Date: Wed, 13 Dec 2017 12:10:26 +0000
> From: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
> To: Jerin Jacob <jerin.jacob@caviumnetworks.com>, Shahaf Shuler
>  <shahafs@mellanox.com>
> CC: "dev@dpdk.org" <dev@dpdk.org>, "Nicolau, Radu"
>  <radu.nicolau@intel.com>, "arybchenko@solarflare.com"
>  <arybchenko@solarflare.com>
> Subject: RE: [dpdk-dev] [PATCH v2 05/39] examples/l3fwd: move to ethdev
>  offloads API
> 
> Hi Jerin,

Hi Konstantin,

> 
> > -----Original Message-----
> > From: Jerin Jacob [mailto:jerin.jacob@caviumnetworks.com]
> > Sent: Wednesday, December 13, 2017 7:55 AM
> > To: Shahaf Shuler <shahafs@mellanox.com>
> > Cc: Ananyev, Konstantin <konstantin.ananyev@intel.com>; dev@dpdk.org; Nicolau, Radu <radu.nicolau@intel.com>;
> > arybchenko@solarflare.com
> > Subject: Re: [dpdk-dev] [PATCH v2 05/39] examples/l3fwd: move to ethdev offloads API
> > 
> > -----Original Message-----
> > > Date: Wed, 13 Dec 2017 07:21:01 +0000
> > > From: Shahaf Shuler <shahafs@mellanox.com>
> > > To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>, "dev@dpdk.org"
> > >  <dev@dpdk.org>, "Nicolau, Radu" <radu.nicolau@intel.com>,
> > >  "arybchenko@solarflare.com" <arybchenko@solarflare.com>
> > > Subject: Re: [dpdk-dev] [PATCH v2 05/39] examples/l3fwd: move to ethdev
> > >  offloads API
> > >
> > > Tuesday, December 12, 2017 7:12 PM, Ananyev, Konstantin:
> > > > > -----Original Message-----
> > > > > From: Shahaf Shuler [mailto:shahafs@mellanox.com]
> > > > > Sent: Tuesday, December 12, 2017 12:26 PM
> > > > > To: dev@dpdk.org; Ananyev, Konstantin
> > > > <konstantin.ananyev@intel.com>;
> > > > > Nicolau, Radu <radu.nicolau@intel.com>; arybchenko@solarflare.com
> > > > > Subject: [PATCH v2 05/39] examples/l3fwd: move to ethdev offloads API
> > > > >
> > > > > Ethdev offloads API has changed since:
> > > > >
> > > > > commit ce17eddefc20 ("ethdev: introduce Rx queue offloads API") commit
> > > > > cba7f53b717d ("ethdev: introduce Tx queue offloads API")
> > > > >
> > > > > This commit support the new API.
> > > > >
> > > > > Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>
> > > > > ---
> > > > >  examples/l3fwd/main.c | 40 ++++++++++++++++++++++++++++++--------
> > > > --
> > > > >  1 file changed, 30 insertions(+), 10 deletions(-)
> > > > >
> > > > > diff --git a/examples/l3fwd/main.c b/examples/l3fwd/main.c index
> > > > > 6229568..3bdf4d5 100644
> > > > > --- a/examples/l3fwd/main.c
> > > > > +++ b/examples/l3fwd/main.c
> > > > > @@ -149,11 +149,9 @@ struct lcore_params {
> > > > >  		.mq_mode = ETH_MQ_RX_RSS,
> > > > >  		.max_rx_pkt_len = ETHER_MAX_LEN,
> > > > >  		.split_hdr_size = 0,
> > > > > -		.header_split   = 0, /**< Header Split disabled */
> > > > > -		.hw_ip_checksum = 1, /**< IP checksum offload enabled */
> > > > > -		.hw_vlan_filter = 0, /**< VLAN filtering disabled */
> > > > > -		.jumbo_frame    = 0, /**< Jumbo Frame Support disabled */
> > > > > -		.hw_strip_crc   = 1, /**< CRC stripped by hardware */
> > > > > +		.ignore_offload_bitfield = 1,
> > > > > +		.offloads = (DEV_RX_OFFLOAD_CRC_STRIP |
> > > > > +			     DEV_RX_OFFLOAD_CHECKSUM),
> > > > >  	},
> > > > >  	.rx_adv_conf = {
> > > > >  		.rss_conf = {
> > > > > @@ -163,6 +161,7 @@ struct lcore_params {
> > > > >  	},
> > > > >  	.txmode = {
> > > > >  		.mq_mode = ETH_MQ_TX_NONE,
> > > > > +		.offloads = DEV_TX_OFFLOAD_MBUF_FAST_FREE,
> > > >
> > > > Hmm, does it mean a new warning for all PMDs (majority) which don't
> > > > support DEV_TX_OFFLOAD_MBUF_FAST_FREE?
> > >
> > > Good point.
> > > Unlike other offloads which are must for the application proper run, this one it only for optimizing the performance and should be set only
> > if PMD supports.
> > > Am continuing to aggregate reasons why the DEV_TX_OFFLOAD_MBUF_FAST_FREE should not be defined as an offload. Anyway we
> > passed that...
> > >
> > > I will fix on v3.
> > 
> > Removing is not an option as the PMDs rely on that flag to will have the
> > impact.
> > # I see DEV_TX_OFFLOAD_MBUF_FAST_FREE as hint driver to depict the application requirements
> > # All the drivers by default can support DEV_TX_OFFLOAD_MBUF_FAST_FREE(They are using the hint or
> > not is a different question)
> > 
> > So, How about setting DEV_TX_OFFLOAD_MBUF_FAST_FREE in all PMD driver as
> > dummy one? I think, currently, it can be moved to old API to new API
> > transition function till the drivers change to new offload flag scheme.
> 
> I don't think anyone plans to remove it right now.
> If you believe your PMD does need it, that's ok by me.

OK.

> Though I still think it is a very limited usage for it, and I don't think
> we have to make that flag supported by all PMDs.

OK. I just suggested because adding the flag in PMD is harmless and we can 
avoid an extra check(setting the DEV_TX_OFFLOAD_MBUF_FAST_FREE only
when PMD supports it) in application to hide warning as you pointed out.
No strong opinion on the specifics, I am just cared only reaching the flag to 
driver.



> Konstantin
> 
> > 
> > We are planning to change nicvf driver to new offload scheme for this
> > release so with this change, we have the performance impact on l3fwd
> > application.
> > 
> > I think, the other option could be to change usage/meaning of
> > DEV_TX_OFFLOAD_MBUF_FAST_FREE flag where when the application needs
> > multi-pool and reference count scheme then "it sets" the offload flags.
> > If so, we don't need to set by default on the these applications.