freebsd stable - Feb 2016 - 82576 + NETMAP + VLAN

I am sorry, I did not participate to the implementation of kqueue 
support and I am not able to comment. Luigi and Adrian should know, however.

Cheers,
Giuseppe

Il 15/02/2016 22:44, Slawa Olhovchenkov ha scritto:
> On Mon, Feb 15, 2016 at 05:02:36PM +0100, Giuseppe Lettieri wrote:
>
>> Il 15/02/2016 16:13, Slawa Olhovchenkov ha scritto:
>>> On Mon, Feb 15, 2016 at 04:10:30PM +0100, Giuseppe Lettieri wrote:
>>>
>>>> Hi Slawa,
>>>>
>>>> I think WITNESS is seeing a false positive, since those two are
always
>>>> different mutexes.
>>>>
>>>> The actual deadlock you experience should be caused by
something else. I
>>>
>>> Are you sure? When deadlock occur I am see threads waiting on
nm_kn_lock.
>>
>> The deadlock I mentioned still involves nm_kn_locks, sorry if I was not
>> clear about that. I am just saying that we never try to take the same
>> lock that we already holding.
>>
>> Nonetheless, there are indeed problems in the path that WITNESS has
>> seen. The problem is that pipes have to notify the other end while
>> called by kevent. kevent holds the nm_kn_lock on the TX src ring and
the
>> notification takes the nm_kn_lock on the RX dst ring.
>
> Can you comment other issuses? Is this by design or is this bug?
>
> - with kevent sync for transmiting need first register
>    EVFILT_WRITE/EV_DISABLE and after every write
>    EVFILT_WRITE/EV_DISPATCH
>
> - with kevent sync all opening /dev/netmap and registering need do
>    from same thread as kevent using for sinc (unless no RX/TX).
>
>

-- 
Dr. Ing. Giuseppe Lettieri
Dipartimento di Ingegneria della Informazione
Universita' di Pisa
Largo Lucio Lazzarino 1, 56122 Pisa - Italy
Ph. : (+39) 050-2217.649 (direct) .599 (switch)
Fax : (+39) 050-2217.600
e-mail: g.lettieri at iet.unipi.it

On Tue, Feb 16, 2016 at 11:23:20AM +0100, Giuseppe Lettieri wrote:
> I am sorry, I did not participate to the implementation of kqueue 
> support and I am not able to comment. Luigi and Adrian should know,
however.
Thanks!
> Cheers,
> Giuseppe
> 
> Il 15/02/2016 22:44, Slawa Olhovchenkov ha scritto:
> > On Mon, Feb 15, 2016 at 05:02:36PM +0100, Giuseppe Lettieri wrote:
> >
> >> Il 15/02/2016 16:13, Slawa Olhovchenkov ha scritto:
> >>> On Mon, Feb 15, 2016 at 04:10:30PM +0100, Giuseppe Lettieri
wrote:
> >>>
> >>>> Hi Slawa,
> >>>>
> >>>> I think WITNESS is seeing a false positive, since those
two are always
> >>>> different mutexes.
> >>>>
> >>>> The actual deadlock you experience should be caused by
something else. I
> >>>
> >>> Are you sure? When deadlock occur I am see threads waiting on
nm_kn_lock.
> >>
> >> The deadlock I mentioned still involves nm_kn_locks, sorry if I
was not
> >> clear about that. I am just saying that we never try to take the
same
> >> lock that we already holding.
> >>
> >> Nonetheless, there are indeed problems in the path that WITNESS
has
> >> seen. The problem is that pipes have to notify the other end while
> >> called by kevent. kevent holds the nm_kn_lock on the TX src ring
and the
> >> notification takes the nm_kn_lock on the RX dst ring.
> >
> > Can you comment other issuses? Is this by design or is this bug?
> >
> > - with kevent sync for transmiting need first register
> >    EVFILT_WRITE/EV_DISABLE and after every write
> >    EVFILT_WRITE/EV_DISPATCH
> >
> > - with kevent sync all opening /dev/netmap and registering need do
> >    from same thread as kevent using for sinc (unless no RX/TX).
> >
> >
> 
> 
> -- 
> Dr. Ing. Giuseppe Lettieri
> Dipartimento di Ingegneria della Informazione
> Universita' di Pisa
> Largo Lucio Lazzarino 1, 56122 Pisa - Italy
> Ph. : (+39) 050-2217.649 (direct) .599 (switch)
> Fax : (+39) 050-2217.600
> e-mail: g.lettieri at iet.unipi.it