[ovs-dev] [PATCH v12 00/11] Add offload support for sFlow

[Ilya Maximets]

On 3/1/21 9:30 AM, Chris Mi wrote:
> Hi Simon, Ilya,
> 
> Could I know what should we do to make progress for this patch set?
> It has been posted in the community for a long time 😁

In general, the way to get your patches reviewed is to review other
patches.  It's simply because we still have a huge review backlog
(214 patches right now in patchwork and most of them needs review)
and bugfixes usually has a bit higher priority.  By reviewing other
patches you're reducing amount of work for maintainers so they can
get to your patches faster.

For the series and comments from Eelco:
I didn't read the patches carefully, only a quick glance, but I still
do not understand why we need a separate thread to poll psample events.
Why can't we just allow usual handler threads to do that?  From the
architecture perspective it's not a good thing to call ofproto code
from the offload-provider.  This introduces lots of complications
and might cause lots of issues in the future.

I'd say that design should look like this:

  handler thread ->
    dpif_recv() ->
      dpif_netlink_recv() ->
        netdev_offload_recv() ->
          netdev_offload_tc_recv() ->
            nl_sock_recv()

Last three calls should be implemented.

The better version of this will be to throw away dpif part from
above call chain and make it:

  handler thread ->
    netdev_offload_recv() ->
      netdev_offload_tc_recv() ->
        nl_sock_recv()

This way we could avoid touching dpif-netdev and still have psample
offloading for the case where netdev-offload-tc is used from the
userspace datapath.

Above architecture also implies implementation of:
 - netdev_offload_recv_wait()
 - netdev_offload_recv_purge()
 - and the netdev_offload_tc_* counterparts.

Best regards, Ilya Maximets.

> 
> Thanks,
> Chris
> 
> On 2/23/2021 5:08 PM, Roi Dayan wrote:
>>
>>
>> On 2021-01-27 8:23 AM, Chris Mi wrote:
>>> This patch set adds offload support for sFlow.
>>>
>>> Psample is a genetlink channel for packet sampling. TC action act_sample
>>> uses psample to send sampled packets to userspace.
>>>
>>> When offloading sample action to TC, userspace creates a unique ID to
>>> map sFlow action and tunnel info and passes this ID to kernel instead
>>> of the sFlow info. psample will send this ID and sampled packet to
>>> userspace. Using the ID, userspace can recover the sFlow info and send
>>> sampled packet to the right sFlow monitoring host.
>>>
>>> v2-v1:
>>> - Fix robot errors.
>>> v3-v2:
>>> - Remove Gerrit Change-Id.
>>> - Add patch #9 to fix older kernels build issue.
>>> - Add travis test result.
>>> v4-v3:
>>> - Fix offload issue when sampling rate is 1.
>>> v5-v4:
>>> - Move polling thread from ofproto to netdev-offload-tc.
>>> v6-v5:
>>> - Rebase.
>>> - Add GitHub Actions test result.
>>> v7-v6:
>>> - Remove Gerrit Change-Id.
>>> - Fix "ERROR: Inappropriate spacing around cast"
>>> v8-v7
>>> - Address Eelco Chaudron's comment for patch #11.
>>> v9-v8
>>> - Remove sflow_len from struct dpif_sflow_attr.
>>> - Log a debug message for other userspace actions.
>>> v10-v9
>>> - Address Eelco Chaudron's comments on v9.
>>> v11-v10
>>> - Fix a bracing error.
>>> v12-v11
>>> - Add duplicate sample group id check.
>>>
>>> Chris Mi (11):
>>>    compat: Add psample and tc sample action defines for older kernels
>>>    ovs-kmod-ctl: Load kernel module psample
>>>    dpif: Introduce register sFlow upcall callback API
>>>    ofproto: Add upcall callback to process sFlow packet
>>>    netdev-offload: Introduce register sFlow upcall callback API
>>>    netdev-offload-tc: Implement register sFlow upcall callback API
>>>    dpif-netlink: Implement register sFlow upcall callback API
>>>    netdev-offload-tc: Introduce group ID management API
>>>    netdev-offload-tc: Create psample netlink socket
>>>    netdev-offload-tc: Add psample receive handler
>>>    netdev-offload-tc: Add offload support for sFlow
>>>
>>>   include/linux/automake.mk        |   4 +-
>>>   include/linux/psample.h          |  58 +++
>>>   include/linux/tc_act/tc_sample.h |  25 ++
>>>   lib/dpif-netdev.c                |   1 +
>>>   lib/dpif-netlink.c               |  27 ++
>>>   lib/dpif-netlink.h               |   4 +
>>>   lib/dpif-provider.h              |  10 +
>>>   lib/dpif.c                       |   8 +
>>>   lib/dpif.h                       |  23 ++
>>>   lib/netdev-offload-provider.h    |   3 +
>>>   lib/netdev-offload-tc.c          | 659 ++++++++++++++++++++++++++++++-
>>>   lib/netdev-offload.c             |  30 ++
>>>   lib/netdev-offload.h             |   4 +
>>>   lib/tc.c                         |  61 ++-
>>>   lib/tc.h                         |  16 +-
>>>   ofproto/ofproto-dpif-upcall.c    |  42 ++
>>>   utilities/ovs-kmod-ctl.in        |  14 +
>>>   17 files changed, 973 insertions(+), 16 deletions(-)
>>>   create mode 100644 include/linux/psample.h
>>>   create mode 100644 include/linux/tc_act/tc_sample.h
>>>
>>
>>
>> Hi Simon, Ilya,
>>
>> Can you help review for this series?
>> do you have any comments you want us to handle?
>>
>> Thanks,
>> Roi
>