Re: [Bluez-users] [Bluez Users] Page timeout during sdp on heavy traffic.

["Emanuele Novelli" <ema.novelli@gmail.com>]

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2007/5/29, Marcel Holtmann <marcel@holtmann.org>:
>
> Hi Emanuele,
>
> > I wrote a little application to simulate an heavy traffic.
> > Simply discovers devices using hci0 and for each device discovered
> > starts a thread to search service using hci1.
> > Rinse and repeat forever.
> > Usually I have 5-6 bluetooth devices in the area.
> > I'm not using d-bus messaging (yet) but i guess i'll try that too to
> > check
> >
> > Anyway I noticed a large number of timeouts during search services on
> > devices who previously returned correct service record.
>
> I have no idea how often I have to say that, but you can't page devices
> at the same time. The chips simply don't support that. The same reason
> why you can run an inquiry and page at the same time. It is not
> possible. Period. And this means you have to serialize the SDP service
> requests.
>
> New kernel versions try to handling pending page attempts for piconet
> creation, but that is also limited. And simultaneous name resolve
> request can also cause troubles.
>
> Regards
>
> Marcel
>
>
Maybe I was not clear sorry, the sdp search I do on hci1 is serialized. It's
a thread started each one a new device is discovered. He does 1 sdp search
and quit. Then another one is started on next device on the list of the
discovered ones.

I know I cant do inquiry and page at same time but I read elsewhere on this
forum that using 2 separate hci at once you can actually achieve that. But
maybe I was wrong if so sorry for the silly question.
Simply I do inquiry with hci0 (never stops) and each time it finds a group
devices I start an sdp search on hci1 (1 device at time serialized) but as I
wrote sometimes this request return page timeout while other time it works
well as per the hcidump I attached on previous message.
At this time the inquiry is always running (not periodic inquiry simply a
looped inquiry request)
That's only to check what's happening on heavy traffic.

Is possible that an inquiry and an sdp on 2 separate threads even if on 2
differents hci can cause problems someway during threads context switch?

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