From: Konstantin Ananyev <konstantin.ananyev@huawei.com>
To: "Morten Brørup" <mb@smartsharesystems.com>,
taozj888 <taozj888@163.com>,
"Stephen Hemminger" <stephen@networkplumber.org>,
"konstantin.v.ananyev@yandex.ru" <konstantin.v.ananyev@yandex.ru>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: RE: Re: [PATCH v3 1/2] examples/l3fwd: relax RSS requirement with option
Date: Mon, 13 Nov 2023 13:19:14 +0000 [thread overview]
Message-ID: <2f9e5942d33a48cc82e0b88a4a3b31ee@huawei.com> (raw)
In-Reply-To: <98CBD80474FA8B44BF855DF32C47DC35E9F01A@smartserver.smartshare.dk>
>> Now the port Rx mq_mode had been set to RTE_ETH_MQ_RX_RSS
>> by default, but some hw and/or virtual interface does not
>> support the RSS and offload mode presupposed, e.g., some
>> virtio interfaces in the cloud don't support
>> RSS and the error msg may like:
>>
>> virtio_dev_configure(): RSS support requested but not supported by
>> the device
>> Port0 dev_configure = -95
>>
>> So to enable the l3fwd running in that environment, the Rx mode requirement
>> can be relaxed to reflect the hardware feature reality here, and the l3fwd
>> can run smoothly then.
>>
>> An option named "relax-rx-mode" is added to enable the relax action
>> here, and it's disabled by default.
>>
>> Signed-off-by: Trevor Tao <mailto:taozj888@163.com>
>
>Doesn't need to be an option. The application can just look at the offload
>flags and quickly determine that if multiple queues are being used than
>RSS is required. If device doesn't support RSS, then fallback to single
>queue with a warning.
>
>Hi Stephen:
>
>I think the option here was suggested/required by Konstantin Ananyev <mailto:konstantin.v.ananyev@yandex.ru>.
>The discussion thread is listed below:
>
">>>>Should we probably instead have a new commnad-line option to explicitly
>>>>disable RSS?
>>>
>>>>Something like: '--no-rss' or so?
>>> Trevor: the RSS capability for a certain port was got by the rte_eth_dev_info_get() automatically, and we think the user should not care about its status beforehand, but if it's missing, a warning notification for the degrade here would be proposed to make it run smoothly.
>>
>>Personally, I still think it would be better the user will
>>have an ability to disable it explicitly.
>>Same as l3fwd does now with 'parse-ptype'.
>>
>
>[Morten]: The "relax-rx-mode" does not explicitly disable RSS, it enables the behavior Stephen suggested: If RSS is not supported by the device, fallback to single queue with a warning. We don't need an option >for this; it should be the default behavior.
>[Morten]: I think Konstantin was asking for an option "no-rss" (or "disable-rss") to force use of single queue (disable RSS), regardless if the device supports RSS or not.
Yes, that what was my initial suggestion: let people explicitly disable RSS if they want to.
BTW, I think it wouldn't change number of HW queues in any way.
It would just disable distribution of packets among HW queues based on RSS.
Konstantin
next prev parent reply other threads:[~2023-11-13 13:19 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-12 7:16 [PATCH v3 0/2] example/l3fwd: relax l3fwd rx RSS/Offload if needed Trevor Tao
2023-11-12 7:16 ` [PATCH v3 1/2] examples/l3fwd: relax RSS requirement with option Trevor Tao
2023-11-12 23:33 ` Stephen Hemminger
2023-11-13 11:47 ` taozj888
2023-11-13 12:40 ` Morten Brørup
2023-11-13 13:19 ` Konstantin Ananyev [this message]
2023-11-13 16:06 ` taozj888
2023-11-12 7:16 ` [PATCH v3 2/2] examples/l3fwd: relax the Offload requirement Trevor Tao
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