[dpdk-dev] [PATCH] event/dsw: avoid reusing previously recorded events

[Mattias Rönnblom]

On 2020-04-14 14:45, Jerin Jacob wrote:
> On Sat, Apr 4, 2020 at 6:05 PM Jerin Jacob <jerinjacobk at gmail.com> wrote:
>> On Fri, Mar 6, 2020 at 11:35 AM Venky Venkatesh
>> <vvenkatesh at paloaltonetworks.com> wrote:
>>> Hi Mattias,
>>> Have a question on this fix. I understand you wanting a certain number of
>>> events before making a decision to migrate (in the above fix).
>>> However, suppose there are fewer events over a few flows (even if not many)
>>> and yet your core is heavily loaded -- indicating may be they are one or
>>> more very CPU intensive flows. Often in DPI situations depending on the
>>> complexity of the policy you can get delayed longer. It might still be
>>> worthwhile to migrate if the other cores are really lightly loaded. I think
>>> that case will be missed out in this approach.
>>>
>>> Fundamentally, the number of packets being a proxy-metric for the load of
>>> that flow on the cpu is simplistic at times. Very CPU intensive
>>> medium/lower bandwidth flows can be picked up in this heuristic. If there
>>> is a way that at the time of DSW init we can have a way of tuning it
>>> depending on the application scenario it might be more flexible.
>> Hi Venky and Mattias,
>>
>> Is this patch to good to merge?
> Please mark the patch as "Not applicable" if the patch is not required.
>

This patch should be merged. Thanks.


>>> Thanks
>>> -Venky
>>>
>>>
>>> On Thu, Mar 5, 2020 at 2:47 AM Mattias Rönnblom <
>>> mattias.ronnblom at ericsson.com> wrote:
>>>
>>>> Avoid reusing recorded events when performing a migration, since this
>>>> may make the migration selection logic pick an already-moved flow.
>>>>
>>>> Fixes: f6257b22e767 ("event/dsw: add load balancing")
>>>> Cc: stable at dpdk.org
>>>>
>>>> Reported-by: Venky Venkatesh <vvenkatesh at paloaltonetworks.com>
>>>> Signed-off-by: Mattias Rönnblom <mattias.ronnblom at ericsson.com>
>>>> ---
>>>>   drivers/event/dsw/dsw_event.c | 3 +++
>>>>   1 file changed, 3 insertions(+)
>>>>
>>>> diff --git a/drivers/event/dsw/dsw_event.c b/drivers/event/dsw/dsw_event.c
>>>> index d68b71b98..296adea18 100644
>>>> --- a/drivers/event/dsw/dsw_event.c
>>>> +++ b/drivers/event/dsw/dsw_event.c
>>>> @@ -646,6 +646,9 @@ dsw_port_consider_migration(struct dsw_evdev *dsw,
>>>>          if (dsw->num_ports == 1)
>>>>                  return;
>>>>
>>>> +       if (seen_events_len < DSW_MAX_EVENTS_RECORDED)
>>>> +               return;
>>>> +
>>>>          DSW_LOG_DP_PORT(DEBUG, source_port->id, "Considering
>>>> migration.\n");
>>>>
>>>>          /* Randomize interval to avoid having all threads considering
>>>> --
>>>> 2.17.1
>>>>
>>>>