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
- 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.
- 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.
//Eelco
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