Re: [RFC] ethdev: remove all offload API

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 6/11/2018 12:35 PM, Shahaf Shuler wrote:
> Monday, June 11, 2018 2:26 PM, Ananyev, Konstantin:
>> Cc: dev@dpdk.org
>> Subject: Re: [dpdk-dev] [RFC] ethdev: remove all offload API
>>> Subject: Re: [RFC] ethdev: remove all offload API
>>>
>>> On 6/11/2018 12:00 PM, Shahaf Shuler wrote:
>>>> Hi Ferruh,
>>>>
>>>> Thanks for this patch.
>>>>
>>>> Monday, June 11, 2018 12:10 PM, Ferruh Yigit:
>>>>> Subject: Re: [RFC] ethdev: remove all offload API
>>>>>
>>>>> On 6/9/2018 9:04 AM, Andrew Rybchenko wrote:
>>>>>> On 06/09/2018 01:41 AM, Ferruh Yigit wrote:
>>>>>>> Cc: Shahaf Shuler <shahafs@mellanox.com>
>>>>>>>
>>>>>>> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
>>>>>>> ---
>>>>>>
>>>>>> <...>
>>>>>>
>>>>>>> diff --git a/app/test-eventdev/test_perf_common.c
>>>>>>> b/app/test-eventdev/test_perf_common.c
>>>>>>> index d00f91802..9fe042ffe 100644
>>>>>>> --- a/app/test-eventdev/test_perf_common.c
>>>>>>> +++ b/app/test-eventdev/test_perf_common.c
>>>>>>> @@ -680,13 +680,7 @@ perf_ethdev_setup(struct evt_test *test,
>>>>>>> struct
>>>>> evt_options *opt)
>>>>>>>  			.mq_mode = ETH_MQ_RX_RSS,
>>>>>>>  			.max_rx_pkt_len = ETHER_MAX_LEN,
>>>>>>>  			.split_hdr_size = 0,
>>>>>>> -			.header_split   = 0,
>>>>>>> -			.hw_ip_checksum = 0,
>>>>>>> -			.hw_vlan_filter = 0,
>>>>>>> -			.hw_vlan_strip  = 0,
>>>>>>> -			.hw_vlan_extend = 0,
>>>>>>>  			.jumbo_frame    = 0,
>>>>>>> -			.hw_strip_crc   = 1,
>>>>>>
>>>>>
>>>>> Hi Andrew,
>>>>>
>>>>>> I have 2 questions here:
>>>>>>  1. Why is jumbo_frame kept? There is
>>>>> DEV_RX_OFFLOAD_JUMBO_FRAME.
>>>>>
>>>>> Because there are still some usage of this flag in PMDs, they need
>>>>> to be clarified before removing the flag. I am for removing the
>>>>> flag in final version, but for this RFC I am not able to find enough time to
>> work on PMDs for it.
>>>>
>>>> Can you elaborate?
>>>> Is this something more than just a replace of the jumbo_frame bit with its
>> corresponding flag?
>>>
>>> That was my concern that copy paste won't be enough because some
>>> drivers not just use the jumbo_frame but set it based on
>>> max_rx_pkt_len etc.., that is why left out .jumbo_frame in the RFC.
> 
> I understand the max_rx_pkt_len consideration, but in the end there is some logic which decide if to set/not the jumbo_frame bit. I would expect it just to replace it with the JUMBO_FRAME flag w/o touching the rest of the logic.
> 
> Can you refer to some specific file which you encounter it? 

Hi Shahaf,

There is no specific usage, briefly while preparing RFC I concerned that the
jumbo_frame usage may not be straightforward and just left it in the RFC to not
mislead and postponed to consider later.
As mentioned before jumbo_frame should be replaced in final version of the patch.

Thanks,
ferruh


> 
>>
>> But max_rx_pkt_len need to be remained (and properly processed anyway)
>> no?
>> BTW, I always wonder is there any reason to have jumbo_frame flag at all (as
>> we do have max_rx_pkt_len anyway)?
> 
> I share the same thought, and it was expressed in multiple threads. There is more - {MTU, SCATTER, JUMBO_FRAME}, all are connected and depended only on max_rx_pkt_len and mbuf size. 
> However I think it is too much work to include into this RFC and completely orthogonal. 
> 
>> Konstantin
>>
>>>
>>>>
>>>>>
>>>>>>  2. Why is hw_strip_crc=1 discarded? Yes, I remember plans to make
>>>>>> it
>>>>>>      default behaviour and introduce flag to keep CRC, but right
>>>>>> now the
>>>>>>      patch looks like mixture of two changes which is not good.
>>>>>
>>>>> Yes it is wrong, app should replace "".hw_strip_crc=1 with KEEP_CRC
>> offload.
>>>>> Since both are RFC, kind of hard to maintain, but I think good to
>>>>> create a dependency from this patch to KEEP_CRC one.
>>>>>
>>>>>>
>>>>>> There are more cases in the patch where hw_strip_crc=1 is simply
>>>>> discarded.
>>>>>>
>>>>>> <...>
>>>>>>
>>>>>>> diff --git a/drivers/net/sfc/sfc_ethdev.c
>>>>>>> b/drivers/net/sfc/sfc_ethdev.c index 1b6499f85..ee8ae5b9f 100644
>>>>>>> --- a/drivers/net/sfc/sfc_ethdev.c
>>>>>>> +++ b/drivers/net/sfc/sfc_ethdev.c
>>>>>>> @@ -1089,7 +1089,6 @@ sfc_tx_queue_info_get(struct rte_eth_dev
>>>>> *dev,
>>>>>>> uint16_t tx_queue_id,
>>>>>>>
>>>>>>>  	memset(qinfo, 0, sizeof(*qinfo));
>>>>>>>
>>>>>>> -	qinfo->conf.txq_flags = txq_info->txq->flags;
>>>>>>>  	qinfo->conf.offloads = txq_info->txq->offloads;
>>>>>>>  	qinfo->conf.tx_free_thresh = txq_info->txq->free_thresh;
>>>>>>>  	qinfo->conf.tx_deferred_start = txq_info->deferred_start;
>> diff
>>>>>>> --git a/drivers/net/sfc/sfc_rx.c b/drivers/net/sfc/sfc_rx.c index
>>>>>>> cc76a5b15..58a0df583 100644
>>>>>>> --- a/drivers/net/sfc/sfc_rx.c
>>>>>>> +++ b/drivers/net/sfc/sfc_rx.c
>>>>>>> @@ -1446,7 +1446,6 @@ sfc_rx_check_mode(struct sfc_adapter *sa,
>>>>> struct rte_eth_rxmode *rxmode)
>>>>>>>  	if (~rxmode->offloads & DEV_RX_OFFLOAD_CRC_STRIP) {
>>>>>>>  		sfc_warn(sa, "FCS stripping cannot be disabled -
>> always on");
>>>>>>>  		rxmode->offloads |= DEV_RX_OFFLOAD_CRC_STRIP;
>>>>>>> -		rxmode->hw_strip_crc = 1;
>>>>>>>  	}
>>>>>>>
>>>>>>>  	return rc;
>>>>>>> diff --git a/drivers/net/sfc/sfc_tx.c b/drivers/net/sfc/sfc_tx.c
>>>>>>> index 1bcc2c697..6d42a1a65 100644
>>>>>>> --- a/drivers/net/sfc/sfc_tx.c
>>>>>>> +++ b/drivers/net/sfc/sfc_tx.c
>>>>>>> @@ -171,7 +171,6 @@ sfc_tx_qinit(struct sfc_adapter *sa, unsigned
>>>>>>> int
>>>>> sw_index,
>>>>>>>  	txq->free_thresh =
>>>>>>>  		(tx_conf->tx_free_thresh) ? tx_conf-
>>> tx_free_thresh :
>>>>>>>  		SFC_TX_DEFAULT_FREE_THRESH;
>>>>>>> -	txq->flags = tx_conf->txq_flags;
>>>>>>>  	txq->offloads = offloads;
>>>>>>>
>>>>>>>  	rc = sfc_dma_alloc(sa, "txq", sw_index,
>>>>>>> EFX_TXQ_SIZE(txq_info->entries), @@ -182,7 +181,6 @@
>>>>> sfc_tx_qinit(struct sfc_adapter *sa, unsigned int sw_index,
>>>>>>>  	memset(&info, 0, sizeof(info));
>>>>>>>  	info.max_fill_level = txq_max_fill_level;
>>>>>>>  	info.free_thresh = txq->free_thresh;
>>>>>>> -	info.flags = tx_conf->txq_flags;
>>>>>>>  	info.offloads = offloads;
>>>>>>>  	info.txq_entries = txq_info->entries;
>>>>>>>  	info.dma_desc_size_max = encp-
>>> enc_tx_dma_desc_size_max;
>>>>> @@ -431,18
>>>>>>> +429,10 @@ sfc_tx_qstart(struct sfc_adapter *sa, unsigned int
>>>>>>> +sw_index)
>>>>>>>  	if (rc != 0)
>>>>>>>  		goto fail_ev_qstart;
>>>>>>>
>>>>>>> -	/*
>>>>>>> -	 * The absence of ETH_TXQ_FLAGS_IGNORE is associated
>> with a
>>>>> legacy
>>>>>>> -	 * application which expects that IPv4 checksum offload is
>> enabled
>>>>>>> -	 * all the time as there is no legacy flag to turn off the offload.
>>>>>>> -	 */
>>>>>>> -	if ((txq->offloads & DEV_TX_OFFLOAD_IPV4_CKSUM) ||
>>>>>>> -	    (~txq->flags & ETH_TXQ_FLAGS_IGNORE))
>>>>>>> +	if (txq->offloads & DEV_TX_OFFLOAD_IPV4_CKSUM)
>>>>>>>  		flags |= EFX_TXQ_CKSUM_IPV4;
>>>>>>>
>>>>>>> -	if ((txq->offloads &
>> DEV_TX_OFFLOAD_OUTER_IPV4_CKSUM) ||
>>>>>>> -	    ((~txq->flags & ETH_TXQ_FLAGS_IGNORE) &&
>>>>>>> -	     (offloads_supported &
>>>>> DEV_TX_OFFLOAD_OUTER_IPV4_CKSUM)))
>>>>>>> +	if (txq->offloads & DEV_TX_OFFLOAD_OUTER_IPV4_CKSUM)
>>>>>>>  		flags |= EFX_TXQ_CKSUM_INNER_IPV4;
>>>>>>>
>>>>>>>  	if ((txq->offloads & DEV_TX_OFFLOAD_TCP_CKSUM) || @@
>> -453,16
>>>>> +443,7
>>>>>>> @@ sfc_tx_qstart(struct sfc_adapter *sa, unsigned int sw_index)
>>>>>>>  			flags |= EFX_TXQ_CKSUM_INNER_TCPUDP;
>>>>>>>  	}
>>>>>>>
>>>>>>> -	/*
>>>>>>> -	 * The absence of ETH_TXQ_FLAGS_IGNORE is associated
>> with a
>>>>> legacy
>>>>>>> -	 * application. In turn, the absence of
>> ETH_TXQ_FLAGS_NOXSUMTCP
>>>>> is
>>>>>>> -	 * associated specifically with a legacy application which
>> expects
>>>>>>> -	 * both TCP checksum offload and TSO to be enabled
>> because the
>>>>> legacy
>>>>>>> -	 * API does not provide a dedicated mechanism to control
>> TSO.
>>>>>>> -	 */
>>>>>>> -	if ((txq->offloads & DEV_TX_OFFLOAD_TCP_TSO) ||
>>>>>>> -	    ((~txq->flags & ETH_TXQ_FLAGS_IGNORE) &&
>>>>>>> -	     (~txq->flags & ETH_TXQ_FLAGS_NOXSUMTCP)))
>>>>>>> +	if (txq->offloads & DEV_TX_OFFLOAD_TCP_TSO)
>>>>>>>  		flags |= EFX_TXQ_FATSOV2;
>>>>>>>
>>>>>>>  	rc = efx_tx_qcreate(sa->nic, sw_index, 0, &txq->mem,
>>>>>>
>>>>>> net/sfc changes looks good.
>>>>>> Plus 'struct sfc_txq -> flags' (drivers/net/sfc/sfc_tx.h) and
>>>>>> 'struct sfc_dp_tx_qcreate_info -> flags'
>>>>>> (drivers/net/sfc/sfc_dp_tx.h) should be removed since there are not
>> used now.
>>>>>>
>>>>>> If finally rxmode.jumbo_frame is removed, it should removed from
>>>>>> net/sfc as well (but compiler will help to find it in any case).
>>>>>>
>>>>>> After applying the patch:
>>>>>> $ git grep ETH_TXQ_FLAGS
>>>>>> drivers/net/fm10k/fm10k.h:#define FM10K_SIMPLE_TX_FLAG
>>>>>> ((uint32_t)ETH_TXQ_FLAGS_NOMULTSEGS | \
>>>>>> drivers/net/fm10k/fm10k.h:
>>>>>> ETH_TXQ_FLAGS_NOOFFLOADS)
>>>>>
>>>>> Thanks, will remove this too.
>>>>>
>>>>>>
>>>>>> In general I think that we should do it ASAP. Also it will
>>>>>> guarantee that new PMDs do not use corresponding structure
>> members etc.
>>>>>
>>>>> +1, +1
>>>>
>