On 2/23/23 12:24, Chris Mi wrote:
> Hi Ilya,
>
> Sorry for late response. Please see my comments in-line.
>
> On 1/17/2023 11:00 PM, Ilya Maximets wrote:
>> On 3/17/22 02:12, 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.
>>> v13-v12
>>> - Remove the psample poll thread from netdev-offload-tc and reuse
>>> ofproto handler thread according to Ilya's new desgin.
>>> - Add dpif-offload-provider layer according to Eli's suggestion.
>>> v14-v13
>>> - Fix a robot error.
>>> v15-v14
>>> - Address Eelco Chaudron's comments on v14.
>>> v16-v15
>>> - Address Eelco Chaudron's comments on v15.
>>> - Add two test cases.
>>> v17-v16
>>> - Address Eelco Chaudron's comments on v16.
>>> - Move struct dpif_offload_api from struct dpif_class to struct dpif.
>>> v18-v17
>>> - Rename dpif_offload_api to dpif_offload_class.
>>> - Add init and destroy callbacks in dpif_offload_class. They are called
>>> when registering dpif_offload_class.
>>> v19-18
>>> - Fix a bug that psample_sock is destroyed when last bridge is deleted.
>>> v20-19
>>> - Move buf_stub to struct dpif_offload_sflow avoid garbage values when
>>> ofproto proceses the sampled packet.
>>> v21-20
>>> - Remove netdev dummy for dpif-offload according to Eelco's comment.
>>>
>>> Chris Mi (8):
>>> compat: Add psample and tc sample action defines for older kernels
>>> ovs-kmod-ctl: Load kernel module psample
>>> dpif-offload-provider: Introduce dpif-offload-provider layer
>>> netdev-offload-tc: Introduce group ID management API
>>> dpif-offload-netlink: Implement dpif-offload-provider API
>>> ofproto: Introduce API to process sFlow offload packet
>>> netdev-offload-tc: Add offload support for sFlow
>>> system-offloads-traffic.at: Add sFlow offload test cases
>>>
>>> NEWS | 1 +
>>> include/linux/automake.mk | 4 +-
>>> include/linux/psample.h | 62 ++++
>>> include/linux/tc_act/tc_sample.h | 25 ++
>>> lib/automake.mk | 3 +
>>> lib/dpif-netdev.c | 3 +-
>>> lib/dpif-netlink.c | 20 +-
>>> lib/dpif-offload-netlink.c | 227 +++++++++++++++
>>> lib/dpif-offload-provider.h | 94 +++++++
>>> lib/dpif-offload.c | 147 ++++++++++
>>> lib/dpif-provider.h | 10 +-
>>> lib/dpif.c | 3 +-
>>> lib/netdev-offload-tc.c | 466 +++++++++++++++++++++++++++++--
>>> lib/netdev-offload.h | 2 +
>>> lib/tc.c | 61 +++-
>>> lib/tc.h | 16 +-
>>> ofproto/ofproto-dpif-upcall.c | 73 +++++
>>> tests/system-offloads-traffic.at | 101 +++++++
>>> utilities/ovs-kmod-ctl.in | 14 +
>>> 19 files changed, 1299 insertions(+), 33 deletions(-)
>>> create mode 100644 include/linux/psample.h
>>> create mode 100644 include/linux/tc_act/tc_sample.h
>>> create mode 100644 lib/dpif-offload-netlink.c
>>> create mode 100644 lib/dpif-offload-provider.h
>>> create mode 100644 lib/dpif-offload.c
>>>
>> Hi, Chris, others.
>>
>> Following up with a summary of what we talked about with Majd during
>> the conference with some additional technical details.
>>
>> The main issue with this patch set right now is an dpif-offload-provider
>> concept. It might make sense on it's own, but as I said before, we
>> need to take 'all or nothing' approach with it, otherwise we'll stuck
>> with a half-baked solution scattered among different parts of OVS and
>> that will be not beneficial from the architecture perspective further
>> complicating already fairly complex solution.
>>
>> The full implementation of the dpif-offload-provider concept is clearly
>> out of scope for the sFlow offload feature, so if we need it, it should
>> be done as a separate architectural change re-working all offload
>> implementations including both tc and rte_flow.
>>
>> What I'm suggesting for the current patch set is to drop the
>> dpif-offload-provider parts and go back to the simple schema with
>> receiving upcalls from the regular dpif-provider. This should make the
>> code simpler and better contained in modules it belongs to.
>>
>> Implementation suggestions:
>>
>> 1. OVS handler thread:
>>
>> recv_upcalls()
>> --> dpif_recv()
>> --> dpif_netlink_recv()
>> if (dpif_netlink_recv_cpu_dispatch() == EAGAIN):
>> --> * netdev_offload_recv()
>> for each registered offload API:
>> --> * flow_api->recv()
>> --> * netdev_offload_tc_recv()
>> if handler.id == 0:
>> Receive psample message,
>> fill the struct dpif_upcall, etc.
>> --> break on success (one of the APIs
>> can starve, but we only have one
>> implementation, so it's not a problem
>> for today.)
>> --> upcall_receive()
>> --> process_upcall()
>>
>> * new functions to implement.
>>
>> Similar call chain for the recv_wait() callback.
> Done.
>> 2. process_offload_sflow() seems to duplicate existing upcall_receive(),
>> I'm not sure why we need that.
> Because I thought it is not good to touch this code to deal with offloads.
The point was that you should not need to touch this code.
The underlying dpif/netdev-offload should construct correct upcall structures,
so it will be transparent for the generic upcall_receive().
> OK, process_offload_sflow() was removed and upcall_receive() is used.
>> 3. lib/id-pool.h or lib/id-fpool.h should probably be used to allocate
>> sample group IDs instead of looping over 'next_sample_group_id'.
> Done.
>> Starving of netdev_offload_recv() can be solved by storing a flag in
>> the dpif_handler structure and alternating the order of receiving
>> normal upcalls and offload upcalls based on that flag, switching it
>> on each call, e.g.:
>>
>>
>> handler = &dpif->handlers[handler_id];
>>
>> if (handler->recv_offload_first) {
>> error = netdev_offload_recv(handler_id, upcall, buf);
>> if (error == EAGAIN) {
>> error = dpif_netlink_recv__(dpif, handler_id, upcall, buf);
>> }
>> } else {
>> error = dpif_netlink_recv__(dpif, handler_id, upcall, buf);
>> if (error == EAGAIN) {
>> error = netdev_offload_recv(handler_id, upcall, buf);
>> }
>> }
>>
>> handler->recv_offload_first = !handler->recv_offload_first;
> Done. Thanks for the sample code.
>
> Thanks,
> Chris
>> Best regards, Ilya Maximets.
>
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