Re: [dpdk-dev] net/failsafe: add default Tx mbuf fast free capability

[Andrew Rybchenko <arybchenko@solarflare.com>]

Hi Ferruh,

On 12/21/18 3:43 PM, Ferruh Yigit wrote:
> On 12/21/2018 12:28 PM, Andrew Rybchenko wrote:
>> On 12/21/18 3:12 PM, Ferruh Yigit wrote:
>>> On 10/12/2018 12:36 PM, Andrew Rybchenko wrote:
>>>> From: Ivan Malov <ivan.malov@oktetlabs.ru>
>>>>
>>>> This capability is reported when supported by the current emitting
>>>> sub-device. Failsafe PMD itself does not excercise fast free logic.
>>> I think overlay device capability reporting already discussed a few times, the
>>> question is if an overlay devices should claim a feature when it depends on
>>> underlay devices?
>> The capability may be reported by the failsafe since it is transparent from
>> fast free logic point of view.
> Why it is transparent? If one of the underlying device doesn't support/claim
> this feature, application can't use this feature with failsafe, isn't it?

tx_offload_capa in failsafe is a mask to apply on sub-device capabilities.
So, if the capability is not supported by any sub-device it will not be 
reported.
As well if there is the capability bit in the mask, it will not be 
reported regardless
sub-devices capabilities. The description for the patch above tries to 
explain it -
it looks like not that successful.

>>> Given that no ack/review given to the patch, I am updating it as rejected.
>> Is it a new policy? I thought that it was vice versa before.
> Hi Andrew,
>
> Yes policy is other-way around indeed, when there is no comment at all default
> behavior is accept, but please take above paragraph as my comment to the patch.

Got it.

> And I was thinking it is a little controversial and there is no support to have
> it, so lets don't get it. What do you think?

I see you motivation.

>>>> Signed-off-by: Ivan Malov <ivan.malov@oktetlabs.ru>
>>>> Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
>>>> ---
>>>>    doc/guides/nics/features/failsafe.ini | 1 +
>>>>    drivers/net/failsafe/failsafe_ops.c   | 1 +
>>>>    2 files changed, 2 insertions(+)
>>>>
>>>> diff --git a/doc/guides/nics/features/failsafe.ini b/doc/guides/nics/features/failsafe.ini
>>>> index e3c4c08f2..b6f3dcee6 100644
>>>> --- a/doc/guides/nics/features/failsafe.ini
>>>> +++ b/doc/guides/nics/features/failsafe.ini
>>>> @@ -7,6 +7,7 @@
>>>>    Link status          = Y
>>>>    Link status event    = Y
>>>>    Rx interrupt         = Y
>>>> +Fast mbuf free       = Y
>>>>    Queue start/stop     = Y
>>>>    Runtime Rx queue setup = Y
>>>>    Runtime Tx queue setup = Y
>>>> diff --git a/drivers/net/failsafe/failsafe_ops.c b/drivers/net/failsafe/failsafe_ops.c
>>>> index 7f8bcd4c6..e3add404b 100644
>>>> --- a/drivers/net/failsafe/failsafe_ops.c
>>>> +++ b/drivers/net/failsafe/failsafe_ops.c
>>>> @@ -78,6 +78,7 @@ static struct rte_eth_dev_info default_infos = {
>>>>    		DEV_RX_OFFLOAD_SECURITY,
>>>>    	.tx_offload_capa =
>>>>    		DEV_TX_OFFLOAD_MULTI_SEGS |
>>>> +		DEV_TX_OFFLOAD_MBUF_FAST_FREE |
>>>>    		DEV_TX_OFFLOAD_IPV4_CKSUM |
>>>>    		DEV_TX_OFFLOAD_UDP_CKSUM |
>>>>    		DEV_TX_OFFLOAD_TCP_CKSUM |
>>>>