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

[Jerin Jacob <jerinjacobk@gmail.com>]

On Tue, Apr 14, 2020 at 6:41 PM Mattias Rönnblom
<mattias.ronnblom@ericsson.com> wrote:
>
> On 2020-04-14 14:45, Jerin Jacob wrote:
> > On Sat, Apr 4, 2020 at 6:05 PM Jerin Jacob <jerinjacobk@gmail.com> wrote:
> >> On Fri, Mar 6, 2020 at 11:35 AM Venky Venkatesh
> >> <vvenkatesh@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.

Sure. I will wait for couple of days on any comments on this patch. If
none, I will merge this.



>
>
> >>> Thanks
> >>> -Venky
> >>>
> >>>
> >>> On Thu, Mar 5, 2020 at 2:47 AM Mattias Rönnblom <
> >>> mattias.ronnblom@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@dpdk.org
> >>>>
> >>>> Reported-by: Venky Venkatesh <vvenkatesh@paloaltonetworks.com>
> >>>> Signed-off-by: Mattias Rönnblom <mattias.ronnblom@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
> >>>>
> >>>>
>