From: Thomas Monjalon <thomas@monjalon.net>
To: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>,
Ori Kam <orika@nvidia.com>,
Michael Savisko <michaelsav@nvidia.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
Ferruh Yigit <ferruh.yigit@xilinx.com>,
Slava Ovsiienko <viacheslavo@nvidia.com>
Subject: Re: [RFC] ethdev: add send to kernel action
Date: Wed, 14 Sep 2022 11:57:28 +0200 [thread overview]
Message-ID: <1759351.3VsfAaAtOV@thomas> (raw)
In-Reply-To: <DS0PR12MB6607474085B25BC053A65D2AAB479@DS0PR12MB6607.namprd12.prod.outlook.com>
13/09/2022 14:09, Michael Savisko:
> From: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
> > On 9/12/22 16:39, Michael Savisko wrote:
> > > From: Thomas Monjalon <thomas@monjalon.net>
> > >> 16/08/2022 11:50, Ferruh Yigit:
> > >>> On 8/11/2022 12:35 PM, Michael Savisko wrote:
> > >>>>
> > >>>> In some cases application may receive a packet that should have
> > >>>> been received by the kernel. In this case application uses KNI or
> > >>>> other means to transfer the packet to the kernel.
> > >>>> This commit introduces rte flow action that the application may use
> > >>>> to route the packet to the kernel while still in the HW.
> > >>>>
> > >>>> Signed-off-by: Michael Savisko <michaelsav@nvidia.com>
> > >>>
> > >>> I assume this only works for bifurcated drivers, right?
> > >>
> > >> This question has not been replied after a month.
> > >> Please let's be more reactive.
> > >
> > > Depends on HW. If it can forward packets to different places then it can also
> > be supported. But in most cases yes - for bifurcated drivers.
> >
> > The action sounds like "do some magic". As far as I know we have no concept of
> > kernel and cooperation with the kernel in DPDK yet.
>
> There's nothing "magical". Kernel is not a part of DPDK, but DPDK can use KNI to transfer messages between application and kernel.
> With bifurcated driver we can have a rule to route the packet matching a pattern (example: IPv4 packets) to the DPDK application and the rest of the traffic will be received by the kernel.
> But if we want to receive most of the traffic in DPDK except specific pattern (example: ICMP packets) that should be processed by the kernel, then it's easier to re-route these packets with a single rule.
> The new action I'm suggesting allows application to route packets directly to the kernel without software involvement, it is a HW offload.
> We see it used when working with bifurcated driver, because the kernel driver and the DPDK driver are sharing the same HW.
>
> > Is it a transfer or non-transfer action?
> > I guess non-transfer, since otherwise the next question is which kernel...
>
> This is an ingress action only.
Should we add this note in the doxygen comment?
This is the wording in the v2 sent today:
+ /*
+ * Send packets to the kernel, without going to userspace at all.
+ * The packets will be received by the kernel driver sharing
+ * the same device as the DPDK port.
+ *
+ * No associated configuration structure.
+ */
+ RTE_FLOW_ACTION_TYPE_SEND_TO_KERNEL,
> > In the case of non-transfer DPDK has a concept of Rx queues which are used to
> > deliver traffic to and we have QUEUE and RSS flow actions to do it.
>
> The idea of this offload action is to route traffic away from the DPDK application.
>
> > The patch adds some magic direction "kernel". Don't we want to control
> > destination queue? RSS?
> > May be we need dedicated control steps to setup kernel Rx queues and than use
> > QUEUE/RSS to direct traffic there?
>
> We have no control of how the kernel is configured.
next prev parent reply other threads:[~2022-09-14 9:57 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-11 11:35 Michael Savisko
2022-08-15 12:02 ` Ori Kam
2022-08-16 9:50 ` Ferruh Yigit
2022-09-12 13:32 ` Thomas Monjalon
2022-09-12 13:39 ` Michael Savisko
2022-09-12 14:41 ` Andrew Rybchenko
2022-09-13 12:09 ` Michael Savisko
2022-09-14 9:57 ` Thomas Monjalon [this message]
2022-09-14 9:32 ` [PATCH v2] " Michael Savisko
2022-09-19 15:50 ` [PATCH v3] " Michael Savisko
2022-09-20 11:08 ` Ori Kam
2022-09-26 13:06 ` Andrew Rybchenko
2022-09-28 14:30 ` Michael Savisko
2022-09-29 14:54 ` [PATCH v4] " Michael Savisko
2022-10-03 7:53 ` Andrew Rybchenko
2022-10-03 8:23 ` Ori Kam
2022-10-03 9:44 ` Andrew Rybchenko
2022-10-03 9:57 ` Ori Kam
2022-10-03 10:47 ` Andrew Rybchenko
2022-10-03 11:06 ` Ori Kam
2022-10-03 11:08 ` Andrew Rybchenko
2022-10-03 16:34 ` [PATCH v5] " Michael Savisko
2022-10-04 7:48 ` Andrew Rybchenko
2022-09-20 10:57 ` [PATCH v2] " Ori Kam
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