On 3 Sep 2021, at 14:02, Eelco Chaudron wrote:
On 15 Jul 2021, at 8:01, 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.
Hi Chris,
One thing missing from this patchset is a test case. I think we
should add it, as I’m going over this manually every patch iteration.
I would add the following:
*
Set the sample rate to 1, send 100 packets and make sure you
receive all of them
o Also, verify the output of “ovs-appctl dpctl/dump-flows
system@ovs-system type=tc” is correct, i.e., matches the
kernel output
*
Set the sample rate to 10, send 100 packets and make sure you
receive 10.
o Also, verify the output of “ovs-appctl dpctl/dump-flows
system@ovs-system type=tc” is correct, i.e., matches the
kernel output
Cheers,
Eelco
PS: I also had a problem where only one packet got sent to the
collector, and then no more packets would arrive. Of course, when
I added some debug code, it never happened, and when removing the
debug code, it also worked fine :( Did you ever experience
something like this? I will play a bit more when reviewing
specific code, maybe it will happen again.
One additional thing I’m seeing is the following:
$ ovs-appctl dpctl/dump-flows system@ovs-system type=tc
recirc_id(0),in_port(3),eth(src=52:54:00:88:51:38,dst=04:f4:bc:28:57:01),eth_type(0x0800),ipv4(frag=no),
packets:7144, bytes:600096, used:7.430s,
actions:sample(sample=10.0%,actions(userspace(pid=3925927229,sFlow(vid=0,pcp=0,output=2147483650),actions))),2
Sometimes I get a rather large sFlow(output=) value in the sFlow output.
Converting the above to hex, 0x80000002, where I see this in fix_sflow_action()
as being mentioned multiple output ports? This seems wrong to me as it should
be 3 (as it always is in the none hw offload case). This odd value is also
reported to the sFlow samples.
Unfortunately, I do not have a reproducer for this.
