[Xenomai-help] two questions about using rtdm

[Xenomai-help] two questions about using rtdm

[Landau, Bracha]

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Sent: Monday, July 31, 2006 1:00 PM
To: xenomai@xenomai.org
Subject: Xenomai-help Digest, Vol 10, Issue 48


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Today's Topics:

   1. Re: Beginner's question / testsuite / latency (Jan Kiszka)
   2. Re: Beginner's question / testsuite / latency (Philippe Gerum)


----------------------------------------------------------------------

Message: 1
Date: Mon, 31 Jul 2006 00:00:44 +0200
From: Jan Kiszka <jan.kiszka@domain.hid>
Subject: Re: [Xenomai-help] Beginner's question / testsuite / latency
To: rpm@xenomai.org
Cc: xenomai@xenomai.org
Message-ID: <44CD2C0C.3@domain.hid>
Content-Type: text/plain; charset="iso-8859-15"

Philippe Gerum wrote:
> On Sun, 2006-07-30 at 21:33 +0200, Jan Kiszka wrote:
>> Philippe Gerum wrote:
>>> On Sat, 2006-07-29 at 16:20 +0200, Jan Kiszka wrote:
>>>>>> :|func        6   xnintr_clock_handler (__ipipe_dispatch_wired)
>>>>>> :|func        6   xnintr_irq_handler (xnintr_clock_handler)
>>>>>> :|func        7   xnpod_announce_tick (xnintr_irq_handler)
>>>>>> :|func        8+  xntimer_do_tick_aperiodic (xnpod_announce_tick)
>>>>>> :|func        9   xnthread_periodic_handler (xntimer_do_tick_aperiodic)
>>>>>> :|func       10   xnpod_resume_thread (xnthread_periodic_handler)
>>>>>> :|[21559]    11+  xnpod_resume_thread (xnthread_periodic_handler)
>>>>>> :|func       13+  xnthread_periodic_handler (xntimer_do_tick_aperiodic)
>>>> ...
>>>>
>>>>>> :|func      363+  xnthread_periodic_handler (xntimer_do_tick_aperiodic)
>>>> That are a lot of overruns. Haven't counted, but it should be one
>>>> xnthread_periodic_handler per missed 100 us period (20000 / 100 = 200!).
>>>> [BTW, I think we should handle even this failure scenario without
>>>> looping.
Two questions regarding rtdm:

1) I would like to use the real-time system calls (bind,socket,send,recv, etc) that are included in the API (i.e., rt_dev_socket, rt_dev_bind...).
I tried to replace the calls to their rt equivalents (e.g., socket becomes rt_dev_socket). But apparently that is not enough, because when I do a call to rt_dev_socket, I get an error.
Are there any examples of how to use the r/t sockets?

2) I am running on an MPC8247 with two CPM serial ports. Can I use the 16650A driver provided by xenomai to "impersonate" the CPM serial driver? If not, can you instruct me how to do this?

Bracha
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Re: [Xenomai-help] two questions about using rtdm

[Jan Kiszka]

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Landau, Bracha wrote:
> 
> -----Original Message-----
> From: xenomai-help-bounces@domain.hid
> [mailto:xenomai-help-bounces@domain.hid Behalf Of
> xenomai-help-request@domain.hid

<snip>

Could you please avoid re-using posted mails for new threads? Thanks.

> Two questions regarding rtdm:
> 
> 1) I would like to use the real-time system calls (bind,socket,send,recv, etc) that are included in the API (i.e., rt_dev_socket, rt_dev_bind...).
> I tried to replace the calls to their rt equivalents (e.g., socket becomes rt_dev_socket). But apparently that is not enough, because when I do a call to rt_dev_socket, I get an error.
> Are there any examples of how to use the r/t sockets?

RTnet for real-time networking over Ethernet, Firewire (eth1394 together
with the RT-FireWire package), or WLAN (experimental rt2x00). Soon to
come: RT-CAN via socket interface (patch is working, Wolfgang is
currently cleaning up). Ah, and the special-purpose protocol driver TiMS
(Tiny Messaging Service) that comes with RACK
(developer.berlios.de/projects/rack).

If you are missing something, feel free to write and register your own
RTDM protocol driver. ;)

> 
> 2) I am running on an MPC8247 with two CPM serial ports. Can I use the 16650A driver provided by xenomai to "impersonate" the CPM serial driver? If not, can you instruct me how to do this?

That's one for the PPC experts, but I bet the UART is not compatible
with the 16550A controller, is it?

Jan


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Re: [Xenomai-help] two questions about using rtdm

[Wolfgang Grandegger]

Jan Kiszka wrote:
> Landau, Bracha wrote:
>> -----Original Message-----
>> From: xenomai-help-bounces@domain.hid
>> [mailto:xenomai-help-bounces@domain.hid Behalf Of
>> xenomai-help-request@domain.hid
> 
> <snip>
> 
> Could you please avoid re-using posted mails for new threads? Thanks.
> 
>> Two questions regarding rtdm:
>>
>> 1) I would like to use the real-time system calls (bind,socket,send,recv, etc) that are included in the API (i.e., rt_dev_socket, rt_dev_bind...).
>> I tried to replace the calls to their rt equivalents (e.g., socket becomes rt_dev_socket). But apparently that is not enough, because when I do a call to rt_dev_socket, I get an error.
>> Are there any examples of how to use the r/t sockets?
> 
> RTnet for real-time networking over Ethernet, Firewire (eth1394 together
> with the RT-FireWire package), or WLAN (experimental rt2x00). Soon to
> come: RT-CAN via socket interface (patch is working, Wolfgang is
> currently cleaning up). Ah, and the special-purpose protocol driver TiMS
> (Tiny Messaging Service) that comes with RACK
> (developer.berlios.de/projects/rack).
> 
> If you are missing something, feel free to write and register your own
> RTDM protocol driver. ;)
> 
>> 2) I am running on an MPC8247 with two CPM serial ports. Can I use the 16650A driver provided by xenomai to "impersonate" the CPM serial driver? If not, can you instruct me how to do this?
> 
> That's one for the PPC experts, but I bet the UART is not compatible
> with the 16550A controller, is it?

It is _not_ compatible and it requires porting to RTDM.

Wolfgang.

RE: [Xenomai-help] two questions about using rtdm

[Landau, Bracha]

I downloaded RTNet and tried to compile it for mpc8260 fcc enet. 
I use linux kernel 2.6.14.
The file drivers/rt_mpc8260_fcc_enet.c did not compile. It's looking for files named "immap_8260.h" and "immap_cpm2.h", neither of which exists.


-----Original Message-----
From: Wolfgang Grandegger [mailto:wg@domain.hid]
Sent: Monday, July 31, 2006 3:03 PM
To: Jan Kiszka
Cc: Landau, Bracha; xenomai@xenomai.org
Subject: Re: [Xenomai-help] two questions about using rtdm


Jan Kiszka wrote:
> Landau, Bracha wrote:
>> -----Original Message-----
>> From: xenomai-help-bounces@domain.hid
>> [mailto:xenomai-help-bounces@domain.hid Behalf Of
>> xenomai-help-request@domain.hid
> 
> <snip>
> 
> Could you please avoid re-using posted mails for new threads? Thanks.
> 
>> Two questions regarding rtdm:
>>
>> 1) I would like to use the real-time system calls (bind,socket,send,recv, etc) that are included in the API (i.e., rt_dev_socket, rt_dev_bind...).
>> I tried to replace the calls to their rt equivalents (e.g., socket becomes rt_dev_socket). But apparently that is not enough, because when I do a call to rt_dev_socket, I get an error.
>> Are there any examples of how to use the r/t sockets?
> 
> RTnet for real-time networking over Ethernet, Firewire (eth1394 together
> with the RT-FireWire package), or WLAN (experimental rt2x00). Soon to
> come: RT-CAN via socket interface (patch is working, Wolfgang is
> currently cleaning up). Ah, and the special-purpose protocol driver TiMS
> (Tiny Messaging Service) that comes with RACK
> (developer.berlios.de/projects/rack).
> 
> If you are missing something, feel free to write and register your own
> RTDM protocol driver. ;)
> 
>> 2) I am running on an MPC8247 with two CPM serial ports. Can I use the 16650A driver provided by xenomai to "impersonate" the CPM serial driver? If not, can you instruct me how to do this?
> 
> That's one for the PPC experts, but I bet the UART is not compatible
> with the 16550A controller, is it?

It is _not_ compatible and it requires porting to RTDM.

Wolfgang.

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Re: [Xenomai-help] two questions about using rtdm

[Jan Kiszka]

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Landau, Bracha wrote:
> I downloaded RTNet and tried to compile it for mpc8260 fcc enet. 
> I use linux kernel 2.6.14.
> The file drivers/rt_mpc8260_fcc_enet.c did not compile. It's looking for files named "immap_8260.h" and "immap_cpm2.h", neither of which exists.
> 

I think to remember Wolfgang said that 2.6 is not yet supposed to work
with this particular driver. So I better redirect this question for more
details.

But before digging to deep into this: What are you planning to do with
RTnet? My point is if you actually need deterministic network access or
if you may live with relaxed services via normal Linux. It's not that
RTnet is bad :), but it might not be required here.

Jan


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RE: [Xenomai-help] two questions about using rtdm

[Landau, Bracha]

I don't need deterministic network access, but I was hoping it would improve performance.

-----Original Message-----
From: jan.kiszka@domain.hid [mailto:jan.kiszka@domain.hid]
Sent: Monday, July 31, 2006 5:22 PM
To: Landau, Bracha
Cc: Wolfgang Grandegger; xenomai@xenomai.org
Subject: Re: [Xenomai-help] two questions about using rtdm


Landau, Bracha wrote:
> I downloaded RTNet and tried to compile it for mpc8260 fcc enet. 
> I use linux kernel 2.6.14.
> The file drivers/rt_mpc8260_fcc_enet.c did not compile. It's looking for files named "immap_8260.h" and "immap_cpm2.h", neither of which exists.
> 

I think to remember Wolfgang said that 2.6 is not yet supposed to work
with this particular driver. So I better redirect this question for more
details.

But before digging to deep into this: What are you planning to do with
RTnet? My point is if you actually need deterministic network access or
if you may live with relaxed services via normal Linux. It's not that
RTnet is bad :), but it might not be required here.

Jan

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Re: [Xenomai-help] two questions about using rtdm

[Jan Kiszka]

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Landau, Bracha wrote:
> I don't need deterministic network access, but I was hoping it would improve performance.

RTnet is designed to provide services deterministically, which doesn't
necessarily means with improved performance (nevertheless, you /can/
gain performance this way - for supported protocols).

But your problem can be that, by pulling networking services into the
real-time domain of Xenomai, you affect the whole RT-system. If incoming
traffic (e.g. broadcasts) is not strictly bounded and predictable, it
can cause serious harm due to the CPU time spent on dropping or
forwarding it. Just be warned, that RTnet is not a simple "performance
booster".

Jan


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