Re: Problem using tc-sfq with tc-flow for arbitrary hashing

Andy,

Thank you very much for the hint. The command is now accepted.

Unfortunately, I see some strange behaviors when using tc-flow, in the sense that sometimes the bandwidth allocation on a 10Gb/s NIC is far form being fair. It looks like the whole bandwidth is capitalized by a single flow, even if I use a small number of flows, even if I wait a couple of perturbation intervals.
Some other times it works perfectly (apart for throughput degradation, ~8.5Gb/s). Not sure what the cause is, but if I use tc-sfq alone without tc-flow iI don’t see this behavior, it always works as expected.

I will test further, but if anyone as some hint, that is appreciated.

Thanks,
Carmelo

> On Mar 28, 2017, at 18:07, Andy Furniss <[email protected]> wrote:
> 
> Carmelo Cascone wrote:
>> Hi all,
>> 
>> I have a problem in configuring tc-sfq along with tc-flow. I would like to hash packets not using the UDP/TCP 5-tuple (default beahvior of tc-sfq), but simply the pair <ipsrc, ipdst>. I’m having hard time using tc-flow and finding help on the web, as such I decided to drop an email to this list.
>> 
>> The commands and error I get are:
>> 
>> $ tc qdisc add dev eth6 root handle 1: sfq
>> $ tc filter add dev eth6 parent 1:0 protocol ip prio 1 flow hash keys src,dst perturb 30 divisor 1024
>> RTNETLINK answers: Invalid argument
>> We have an error talking to the kernel
>> 
>> I’m issuing these commands on a Debian 9 with a kernel v4.9.16
>> Please note that the tc filter command is the same used in the tc-sfq documentation.
>> 
>> What am I doing wrong? What is the invalid argument?
> 
> Looking through many years old Qos folder I found a file with an example.
> 
> I don't know why it's not documented, but but adding handle 1 to the
> filter command makes your example work for me, in the sense that it's
> not rejected - didn't test further.
> 
> Historically I would have said putting sfq on root of an eth wouldn't
> do much, but with BQLs maybe things have changed.
> 
>