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

[Jerin Jacob]

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?

>
> 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
> >
> >