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

[Jerin Jacob <jerinjacobk@gmail.com>]

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.


>
> >
> > 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
> > >
> > >