From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 3B65A432D3; Mon, 13 Nov 2023 13:40:19 +0100 (CET) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 0349140279; Mon, 13 Nov 2023 13:40:19 +0100 (CET) Received: from dkmailrelay1.smartsharesystems.com (smartserver.smartsharesystems.com [77.243.40.215]) by mails.dpdk.org (Postfix) with ESMTP id B407E4026C for ; Mon, 13 Nov 2023 13:40:17 +0100 (CET) Received: from smartserver.smartsharesystems.com (smartserver.smartsharesys.local [192.168.4.10]) by dkmailrelay1.smartsharesystems.com (Postfix) with ESMTP id 906CE20633; Mon, 13 Nov 2023 13:40:15 +0100 (CET) Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01DA162E.8C2051F2" Subject: RE: Re: [PATCH v3 1/2] examples/l3fwd: relax RSS requirement with option X-MimeOLE: Produced By Microsoft Exchange V6.5 Date: Mon, 13 Nov 2023 13:40:12 +0100 Message-ID: <98CBD80474FA8B44BF855DF32C47DC35E9F01A@smartserver.smartshare.dk> In-Reply-To: <2645794b.6331.18bc881a674.Coremail.taozj888@163.com> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: Re: [PATCH v3 1/2] examples/l3fwd: relax RSS requirement with option Thread-Index: AdoWJycoSVKOtAEFQS6cH6Hdua6uqAABmVpw References: <20231112071611.101503-1-taozj888@163.com> <20231112071611.101503-2-taozj888@163.com> <20231112153349.202150ff@hermes.local> <2645794b.6331.18bc881a674.Coremail.taozj888@163.com> From: =?iso-8859-1?Q?Morten_Br=F8rup?= To: "taozj888" , "Stephen Hemminger" , Cc: X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org This is a multi-part message in MIME format. ------_=_NextPart_001_01DA162E.8C2051F2 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable From: taozj888 [mailto:taozj888@163.com]=20 Sent: Monday, 13 November 2023 12.47 At 2023-11-13 07:33:49, "Stephen Hemminger" = wrote: >On Sun, 12 Nov 2023 07:16:10 +0000 >Trevor Tao wrote: >=20 >> 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: >>=20 >> virtio_dev_configure(): RSS support requested but not supported by >> the device >> Port0 dev_configure =3D -95 >>=20 >> 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. >>=20 >> An option named "relax-rx-mode" is added to enable the relax action >> here, and it's disabled by default. >>=20 >> Signed-off-by: Trevor Tao >=20 >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. =20 Hi Stephen: =20 I think the option here was suggested/required by Konstantin Ananyev = . The discussion thread is listed below: =20 ">>>>Should we probably instead have a new commnad-line option to = explicitly=20 >>>>disable RSS? >>>=20 >>>>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. >>=20 >>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'. >>=20 " =20 [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. =20 Thanks, =20 Trevor Tao ------_=_NextPart_001_01DA162E.8C2051F2 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

From:= = taozj888 [mailto:taozj888@163.com]
Sent: Monday, 13 November = 2023 12.47

A= t 2023-11-13 07:33:49, "Stephen Hemminger" = <stephen@networkplumber.org> = wrote:

>On Sun, 12 Nov 2023 07:16:10 =
+0000
>Trevor =
Tao <taozj888@163.com> wrote:
> 
>> 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 =3D -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 =
<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:
 <=
/span>
I think the =
option here was suggested/required by Konstantin Ananyev =
<konstantin.v.ananyev@yandex.ru>.
The =
discussion thread is listed =
below:
 <=
/span>
">>>=
>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.
 
Thanks,
 
Trevor =
Tao
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