On 6/10/22 19:08, Davide Caratti wrote:
> hello Greg,
>
> thanks for looking at this!
>
> On Fri, Jun 10, 2022 at 05:09:21PM +0200, Greg KH wrote:
>> On Fri, Jun 10, 2022 at 04:58:37PM +0200, Davide Caratti wrote:
>>> hello,
>>>
>>> Ilya reports bad TCP throughput when GSO packets hit an OVS rule that does
>>> tc MTU policing. According to his observations [1], the problem is fixed
>>> by upstream commit 4ddc844eb81d ("net/sched: act_police: more accurate MTU
>>> policing"). Can we queue this commit for inclusion in stable trees?
>>
>> Did you test this,
>
> I tested it on upstream, RHEL8 and RHEL9 kernels. BTW, the kselftest I included
> in the commit only verifies the correct setting for the MTU threshold, not
> the GSO problem (to test GSO, we should use netperf / iperf3 rather than
> mausezahn to generate traffic).
>
>> and what kernel(s) do you want it applied to?
>
> the reported bug is in act_police since the very beginning; however, the
> patch should apply cleanly at least on 5.x kernels. On older ones, there
> might be a small conflict due to lack of RCU-ification of struct
> tcf_police_params.
> A conflict that gets fixed easily, but in case we need it I volunteer to
> write a patch for kernels older than 4.20. @Ilya, what is the
> minimum kernel usable for openvswitch with MTU policing?
act_police MTU check is supposed to be an alternative for OVS' check_pkt_len()
action which was introduced in 5.2. So, backport to 5.2+ should be enough.
Best regards, Ilya Maximets.
