[ovs-discuss] Drop in performance for conntrack cases with OVS

Darrell Ball dlu998 at gmail.com
Fri Jan 17 04:03:32 UTC 2020


added back the alias

Darrell

On Thu, Jan 16, 2020 at 8:00 PM Darrell Ball <dlu998 at gmail.com> wrote:

> Thanks for the report Anju
>
> Extensive testing was done without tunnels (both PVP and P2P; flows
> 2-100k).
> Threads and queues were also varied.  The testing is about a year old now
> however
> and there were some minor conntrack changes after that, which I would not
> have expected to have a big impact;
> well, at least till now.
>
> This report is interesting however.
>
> 1/ What kind of user traffic - UDP ?
>
> 2/ What about threads and queues ?
>
> Thanks Darrell
>
> On Wed, Jan 15, 2020 at 10:59 PM Anju Thomas via discuss <
> ovs-discuss at openvswitch.org> wrote:
>
>> Hi,
>>
>>
>>
>> We are moving to latest OVS viz OVS 2.12 (Earlier we were on 2.8) . We
>> noticed a significant drop in performance for flows with conntrack (40-50%
>> drop in Traffic going over Vxlan ) . On further analysis , we could pin
>> this drop in performance to the below commit
>>
>>
>>
>> commit 967bb5c5cd9070112138d74a2f4394c50ae48420
>>
>> Author: Darrell Ball <dlu998 at gmail.com>
>>
>> Date:   Thu May 9 08:15:07 2019 -0700
>>
>>
>>
>>     conntrack: Add rcu support.
>>
>>     For performance and code simplification reasons, add rcu support for
>>
>>     conntrack. The array of hmaps is replaced by a cmap as part of this
>>
>>     conversion.  Using a single map also simplifies the handling of NAT
>>
>>     and allows the removal of the nat_conn map and friends.  Per
>> connection
>>
>>     entry locks are introduced, which are needed in a few code paths.
>>
>>
>>
>>
>>
>>
>>
>> Has anyone noticed this and if so is there any way to get around this as
>> well (We don’t use NAT connections)?
>>
>>
>>
>> Is there a specific case where this could give better performance ?
>>
>>
>>
>> Regards
>>
>> Anju
>>
>>
>> _______________________________________________
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>> discuss at openvswitch.org
>> https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
>>
>
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