From: Ferruh Yigit <ferruh.yigit@intel.com>
To: "Loftus, Ciara" <ciara.loftus@intel.com>, "dev@dpdk.org" <dev@dpdk.org>
Cc: "stephen@networkplumber.org" <stephen@networkplumber.org>,
Anatoly Burakov <anatoly.burakov@intel.com>
Subject: Re: [PATCH v2] net/af_xdp: re-enable secondary process support
Date: Mon, 7 Feb 2022 10:27:33 +0000 [thread overview]
Message-ID: <0fa260e7-d5c5-7b92-abd1-b125eb62c6f9@intel.com> (raw)
In-Reply-To: <PH0PR11MB4791B2998C0BD6609D2CE2D48E2C9@PH0PR11MB4791.namprd11.prod.outlook.com>
On 2/7/2022 7:49 AM, Loftus, Ciara wrote:
>>
>> On 2/4/2022 12:54 PM, Ciara Loftus wrote:
>>> Secondary process support had been disabled for the AF_XDP PMD
>>> because there was no logic in place to share the AF_XDP socket
>>> file descriptors between the processes. This commit introduces
>>> this logic using the IPC APIs.
>>>
>>> Since AF_XDP rings are single-producer single-consumer, rx/tx
>>> in the secondary process is disabled. However other operations
>>> including retrieval of stats are permitted.
>>>
>>> Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
>>>
>>> ---
>>> v1 -> v2:
>>> * Rebase to next-net
>>>
>>> RFC -> v1:
>>> * Added newline to af_xdp.rst
>>> * Fixed spelling errors
>>> * Fixed potential NULL dereference in init_internals
>>> * Fixed potential free of address-of expression in afxdp_mp_request_fds
>>> ---
>>> doc/guides/nics/af_xdp.rst | 9 ++
>>> doc/guides/nics/features/af_xdp.ini | 1 +
>>> doc/guides/rel_notes/release_22_03.rst | 1 +
>>> drivers/net/af_xdp/rte_eth_af_xdp.c | 210
>> +++++++++++++++++++++++--
>>> 4 files changed, 207 insertions(+), 14 deletions(-)
>>>
>>> diff --git a/doc/guides/nics/af_xdp.rst b/doc/guides/nics/af_xdp.rst
>>> index db02ea1984..eb4eab28a8 100644
>>> --- a/doc/guides/nics/af_xdp.rst
>>> +++ b/doc/guides/nics/af_xdp.rst
>>> @@ -141,4 +141,13 @@ Limitations
>>> NAPI context from a watchdog timer instead of from softirqs. More
>> information
>>> on this feature can be found at [1].
>>>
>>> +- **Secondary Processes**
>>> +
>>> + Rx and Tx are not supported for secondary processes due to the single-
>> producer
>>> + single-consumer nature of the AF_XDP rings. However other operations
>> including
>>> + statistics retrieval are permitted.
>>
>> Hi Ciara,
>>
>> Isn't this limitation same for all PMDs, like not both primary & secondary can
>> Rx/Tx
>> from same queue at the same time.
>> But primary can initiallize the PMD and secondary can do the datapath,
>> or isn't af_xdp supports multiple queue, if so some queues can be used by
>> primary and some by secondary for datapath.
>>
>> Is there anyhing special for af_xdp that prevents it?
>
> Hi Ferruh,
>
> Thanks for the review.
> Each queue of the PMD corresponds to a new AF_XDP socket.
> Each socket has an RX and TX ring that is mmapped from the kernel to userspace and this mapping is only valid for the primary process.
> I did not figure out a way to share that mapping with the secondary process successfully. Can you think of anything that might work?
>
Does the application knows the buffer address for the Rx/Tx, or is
abstracted to the 'fd'?
If only 'fd' is used, this patch already converts 'fd' between
processes.
cc'ed Anatoly, but what I understand is after MP fd conversion:
Primary process: FD=x
Secondary process: FD=y
And both x & y points to exact same socket in the kernel side.
At least this is how it works for the 'tap' interface, and that is
why 'fs' are in the process_private area and converted between primary
and secondary, I thought it will be same for the xdp socket.
Did you test the secondary Rx/Tx in the secondary after this patch?
next prev parent reply other threads:[~2022-02-07 10:27 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-10 15:32 [RFC PATCH] net/af_xdp: reenable " Ciara Loftus
2021-12-11 21:49 ` Stephen Hemminger
2022-01-12 7:54 ` [PATCH] net/af_xdp: re-enable " Ciara Loftus
2022-02-04 12:54 ` [PATCH v2] " Ciara Loftus
2022-02-04 14:18 ` Ferruh Yigit
2022-02-07 7:49 ` Loftus, Ciara
2022-02-07 10:27 ` Ferruh Yigit [this message]
2022-02-07 11:39 ` Loftus, Ciara
2022-02-08 10:58 ` Ferruh Yigit
2022-02-08 13:48 ` [PATCH v3] " Ciara Loftus
2022-02-08 17:45 ` Stephen Hemminger
2022-02-08 18:00 ` Ferruh Yigit
2022-02-08 18:42 ` Stephen Hemminger
2022-02-08 18:56 ` Ferruh Yigit
2022-02-09 7:41 ` Loftus, Ciara
2022-02-09 9:48 ` [PATCH v4] " Ciara Loftus
2022-02-09 15:29 ` Stephen Hemminger
2022-02-11 13:32 ` Ferruh Yigit
2022-02-09 17:55 ` Ferruh Yigit
2022-02-10 15:08 ` Ferruh Yigit
2022-02-10 15:19 ` Ferruh Yigit
2022-02-10 15:40 ` Loftus, Ciara
2022-02-10 16:06 ` Ferruh Yigit
2022-02-10 17:47 ` Loftus, Ciara
2022-02-10 20:12 ` Ferruh Yigit
2022-02-11 7:28 ` Loftus, Ciara
2022-02-11 9:26 ` Loftus, Ciara
2022-02-11 12:29 ` Ferruh Yigit
2022-02-11 13:01 ` Loftus, Ciara
2022-02-11 13:07 ` Ferruh Yigit
2022-02-11 15:32 ` Loftus, Ciara
2022-02-16 11:23 ` Loftus, Ciara
2022-02-11 11:31 ` Ferruh Yigit
2022-02-17 12:44 ` David Marchand
2022-02-17 12:47 ` Ferruh Yigit
2022-02-17 12:53 ` David Marchand
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=0fa260e7-d5c5-7b92-abd1-b125eb62c6f9@intel.com \
--to=ferruh.yigit@intel.com \
--cc=anatoly.burakov@intel.com \
--cc=ciara.loftus@intel.com \
--cc=dev@dpdk.org \
--cc=stephen@networkplumber.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).