From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: STM32F4 Discovery, communication and libraries
Date: Mon, 1 Sep 2014 18:42:19 +0200
Date: 2014-09-01T18:42:19+02:00 [thread overview]
Message-ID: <wq3x8ean0f5z$.em02okqv4iv8$.dlg@40tude.net> (raw)
In-Reply-To: c6h8ieFfss4U1@mid.individual.net
On Sun, 31 Aug 2014 21:41:15 +0300, Niklas Holsti wrote:
> On 14-08-31 10:02 , Dmitry A. Kazakov wrote:
>> No_Local_Protected_Objects means all requests are pre-allocated at the
>> library level and distributed by another protected object? With busy
>> waiting for a free request?
>
> No, the _request_ in my example code is not a protected object; it is an
> ordinary record type. It _refers_ to a protected object which is a kind
> of "I/O wait object".
That was clear.
>> When I evaluated Ravenscar for our middleware (long ago), the concern was
>> publisher/subscriber services. I/O queue viewed as one of them. I didn't
>> consider a solution like yours because the requirement was that more than
>> one task could await for same I/O event. You reserve the event for single
>> task and other publisher/subscriber services (e.g. the data logger, network
>> data server, health monitor etc) may not use it because of
>> Max_Protected_Entries = 1. The event cannot propagate because of
>> No_Requeue_Statements. Tasks could flood the queue with their
>> requests/events but they cannot do that for more than one queue.
>
> You list a lot of things there... I don't really see how they are
> related to each other, or if they are separate problems.
>
> If for some reason you want to wake up two tasks when one I/O finishes,
> the sample principle can be used: record two references, to two
> protected objects - one per task - in the I/O request, and signal both
> of them when the I/O completes.
That is what I said. But this is only one queue.
> For publish/subscribe, I would do something like this (not tested):
[...]
You don't need anything this complex so long you monitor a single channel.
The challenge is to subscribe to several channels and also to avoid
unnecessary copying of I/O data. Theoretically you could create channels
that are combinations of queues of events to monitor register them by the
queues. I don't know how much overhead it will be (I was trying to reduce
number of protected actions per event), but it looks ugly and overly
complicated.
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
next prev parent reply other threads:[~2014-09-01 16:42 UTC|newest]
Thread overview: 93+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-26 22:38 STM32F4 Discovery, communication and libraries roy.emmerich
2014-08-27 2:40 ` Luke A. Guest
2014-08-27 12:35 ` Roy Emmerich
2014-08-27 7:41 ` Dmitry A. Kazakov
2014-08-27 13:35 ` Roy Emmerich
2014-08-27 16:00 ` Dmitry A. Kazakov
2014-08-27 13:08 ` Dennis Lee Bieber
2014-08-27 15:44 ` Roy Emmerich
2014-08-28 1:37 ` Dennis Lee Bieber
2014-08-27 16:03 ` Roy Emmerich
2014-08-28 1:48 ` Dennis Lee Bieber
2014-08-28 10:12 ` Roy Emmerich
2014-08-28 13:00 ` Dmitry A. Kazakov
2014-08-28 16:28 ` Mike Silva
2014-08-28 17:03 ` Roy Emmerich
2014-08-28 20:09 ` Dmitry A. Kazakov
2014-08-28 20:34 ` embeddedrelatedmike
2014-08-29 7:34 ` Dmitry A. Kazakov
2014-08-29 15:59 ` Niklas Holsti
2014-08-29 16:59 ` [OT] Ravenscar (the place, not profile), was: " Simon Clubley
2014-08-29 17:18 ` Niklas Holsti
2014-08-29 17:31 ` Simon Clubley
2014-08-30 14:55 ` Dennis Lee Bieber
2014-08-29 17:59 ` Jeffrey Carter
2014-08-29 23:30 ` Randy Brukardt
2014-08-30 11:25 ` Simon Clubley
2014-08-31 11:09 ` Phil Thornley
2014-08-30 12:36 ` Peter Chapin
2014-08-31 18:37 ` Dirk Craeynest
2014-08-31 19:38 ` Simon Clubley
2014-08-29 17:24 ` Mike Silva
2014-08-29 23:35 ` Randy Brukardt
2014-08-29 13:06 ` Dennis Lee Bieber
2014-08-29 16:52 ` Niklas Holsti
2014-08-31 0:49 ` Shark8
2014-08-28 21:17 ` Niklas Holsti
2014-08-29 0:07 ` Roy Emmerich
2014-08-29 17:58 ` Niklas Holsti
2014-08-29 7:41 ` Dmitry A. Kazakov
2014-08-29 16:31 ` Niklas Holsti
2014-08-29 16:47 ` Roy Emmerich
2014-08-29 19:41 ` Niklas Holsti
2014-08-30 22:00 ` Roy Emmerich
2014-08-31 10:08 ` Simon Wright
2014-09-01 20:15 ` Niklas Holsti
2014-09-01 21:11 ` Jeffrey Carter
2014-08-31 4:54 ` gvdschoot
2014-09-09 19:17 ` Roy Emmerich
2014-09-09 20:20 ` Mike Silva
[not found] ` <a54dcc42-d4e2-4d53-b381-2bb7a0eef1ee@googlegroups.com>
2014-09-10 1:41 ` Dennis Lee Bieber
2014-09-10 8:52 ` Roy Emmerich
2014-09-10 13:05 ` Dennis Lee Bieber
2014-09-10 17:16 ` Simon Wright
[not found] ` <a2e59fce-751c-46a0-90f3-80430c627732@googlegroups.com>
2014-09-10 7:22 ` Dmitry A. Kazakov
2014-09-10 9:35 ` Roy Emmerich
2014-09-10 14:11 ` Stephen Leake
2014-09-10 17:46 ` Jeffrey Carter
2014-09-10 18:37 ` Dmitry A. Kazakov
2014-09-11 9:53 ` Stephen Leake
2014-09-11 17:19 ` Jeffrey Carter
2014-09-10 20:58 ` Brian Drummond
2014-09-10 23:40 ` Dennis Lee Bieber
2014-08-29 16:58 ` Niklas Holsti
2014-08-31 7:02 ` Dmitry A. Kazakov
2014-08-31 15:44 ` Brad Moore
2014-08-31 16:15 ` Dmitry A. Kazakov
2014-09-01 16:15 ` Brad Moore
2014-09-01 16:42 ` Dmitry A. Kazakov
2014-08-31 18:41 ` Niklas Holsti
2014-09-01 16:42 ` Dmitry A. Kazakov [this message]
2014-09-01 17:21 ` G.B.
2014-09-02 8:21 ` Dmitry A. Kazakov
2014-09-02 13:04 ` G.B.
2014-09-02 14:18 ` Dmitry A. Kazakov
2014-09-02 16:44 ` Jeffrey Carter
2014-09-02 19:02 ` Niklas Holsti
2014-09-02 23:19 ` Randy Brukardt
2014-09-03 1:40 ` gdotone
2014-09-04 9:26 ` Roy Emmerich
2014-09-04 17:58 ` Niklas Holsti
2014-09-05 11:47 ` Simon Clubley
2014-09-09 19:04 ` Roy Emmerich
2014-09-01 18:39 ` Niklas Holsti
2014-09-02 8:19 ` Dmitry A. Kazakov
2014-08-28 13:10 ` Dennis Lee Bieber
2014-08-29 2:52 ` Dennis Lee Bieber
2014-09-20 20:50 ` David Thompson
2014-08-27 16:17 ` Mike Silva
2014-08-27 16:36 ` Roy Emmerich
2014-08-27 16:58 ` Simon Clubley
2014-08-29 19:36 ` johnscpg
2014-08-30 15:06 ` Stephen Leake
2014-09-02 21:40 ` rrr.eee.27
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