Re: [Xenomai-help] LATENCIES > 100 us or CRASH WITH X (with joints pieces)

Re: [Xenomai-help] LATENCIES > 100 us or CRASH WITH X (with joints pieces)

[Jan Kiszka]

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Jean-Luc Pamart wrote:
> Hello
> 
> I am a newbie with Xeno. My goal for the beginning of 2007 is to launch
> a project for 4 french studiants : a box with Linux embedded and a usb
> camera. The embedded application will analyse the movies in Real time
> and lead a mobile machine with CAN-BUS.
> Now i play with Xeno for my knowledge (without specific hardware) :  a
> little linux installed in a usb key with a little embedded distrib
> 
> - vanilla kernel 2.6.16 with patch for usb [.config is joint]
> - Xenomai 2.1.2
> - essentially BusyBox
> - for xenomai : only "latency" directory and libs in usr/libs
> I have checked "SMI woraround" for the kernel.
> In BIOS I have UNchecked  "legacy usb".
> 
> 
> my Desktop PC (a AMD ATHLON) can boot with this little vanilla kernel and
> 1/ a little embedded distrib of my own
> 
> OR
> 
> 2/ a complete mandrake 9.1 on a partition of a classic hard disk
> 
> I have 2 differents problems when I lauch this :
> 
> 1/ with the linux embedded directories on the usb key
> high latency > 100 us are ok ? perhaps usb work is not compatible with RT ?

Try loading the standard USB drivers (at least uhci_hcd) if they aren't
yet. Actually, I've seen boxes (granted, they were far older) where I
had to switch legacy USB *on* to avoid disturbances. In any case, check
carefully if you followed all tips in TROUBLESHOOTING regarding latency
issues (APM, ACPI, etc.).

> 
> 
> 2/ with the complete mandrake 9.1 :
> it crashes X after 1 or few minutes.
> What is the relation between X and Xenomai ?
> Is Xenomai compatible with X ?

Yes, as long as X is not playing against us, e.g. by hard-disabling
interrupts or doing (too) evil things on the buses. Any non-GPL driver
in this game here (NVidia&Co)? Better avoid this. Also try to disable
accelerated mode in your X setup to see if things improve.

Jan


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Re: [Xenomai-help] LATENCIES > 100 us or CRASH WITH X (with joints pieces)

[Jan Kiszka]

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Jean-Luc Pamart wrote:
> Jan Kiszka a écrit :
>> Jean-Luc Pamart wrote:
>>  
>>> Hello
>>>
>>> I am a newbie with Xeno. My goal for the beginning of 2007 is to launch
>>> a project for 4 french studiants : a box with Linux embedded and a usb
>>> camera. The embedded application will analyse the movies in Real time
>>> and lead a mobile machine with CAN-BUS.
>>> Now i play with Xeno for my knowledge (without specific hardware) :  a
>>> little linux installed in a usb key with a little embedded distrib
>>>
>>> - vanilla kernel 2.6.16 with patch for usb [.config is joint]
>>> - Xenomai 2.1.2
>>> - essentially BusyBox
>>> - for xenomai : only "latency" directory and libs in usr/libs
>>> I have checked "SMI woraround" for the kernel.
>>> In BIOS I have UNchecked  "legacy usb".
>>>
>>>
>>> my Desktop PC (a AMD ATHLON) can boot with this little vanilla kernel
>>> and
>>> 1/ a little embedded distrib of my own
>>>
>>> OR
>>>
>>> 2/ a complete mandrake 9.1 on a partition of a classic hard disk
>>>
>>> I have 2 differents problems when I lauch this :
>>>
>>> 1/ with the linux embedded directories on the usb key
>>> high latency > 100 us are ok ? perhaps usb work is not compatible
>>> with RT ?
>>>     
>>
>> Try loading the standard USB drivers (at least uhci_hcd) if they aren't
>> yet. Actually, I've seen boxes (granted, they were far older) where I
>> had to switch legacy USB *on* to avoid disturbances. In any case, check
>> carefully if you followed all tips in TROUBLESHOOTING regarding latency
>> issues (APM, ACPI, etc.).
>>
>>  
>>> 2/ with the complete mandrake 9.1 :
>>> it crashes X after 1 or few minutes.
>>> What is the relation between X and Xenomai ?
>>> Is Xenomai compatible with X ?
>>>     
>>
>> Yes, as long as X is not playing against us, e.g. by hard-disabling
>> interrupts or doing (too) evil things on the buses. Any non-GPL driver
>> in this game here (NVidia&Co)? Better avoid this. Also try to disable
>> accelerated mode in your X setup to see if things improve.
>>
>> Jan
>>
>>   
> Ok , for the box with a vanilla kernel I will try the differents
> possibilities. Actually i disable
> a max of things ...
> 
> For the box with X : the big surprise was : very goods latencies
> (comparativeley with no X !!)
> Why ????
> (Before crashing)

If it turns out to be an ACPI/APM issue, X may keep your box busier than
plain text mode, thus avoid those latency peaks by keeping it out of
certain sleep modes - well, an attempt to explain something I can't with
the currently available information...

> 
> for crashing
> I 'll verify theses 2 points :
> nvidia driver
> accelerated mode  : Is it a x server setup ?
> 

See Gilles' reply => XF86Config.

Jan


PS: Don't forget to reply-to-all.


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Re: [Xenomai-help] LATENCIES > 100 us or CRASH WITH X (with joints pieces)

[Jean-Luc Pamart]

Jan Kiszka a écrit :
> Jean-Luc Pamart wrote:
>   
>> Jan Kiszka a écrit :
>>     
>>> Jean-Luc Pamart wrote:
>>>  
>>>       
>>>> Hello
>>>>
>>>> I am a newbie with Xeno. My goal for the beginning of 2007 is to launch
>>>> a project for 4 french studiants : a box with Linux embedded and a usb
>>>> camera. The embedded application will analyse the movies in Real time
>>>> and lead a mobile machine with CAN-BUS.
>>>> Now i play with Xeno for my knowledge (without specific hardware) :  a
>>>> little linux installed in a usb key with a little embedded distrib
>>>>
>>>> - vanilla kernel 2.6.16 with patch for usb [.config is joint]
>>>> - Xenomai 2.1.2
>>>> - essentially BusyBox
>>>> - for xenomai : only "latency" directory and libs in usr/libs
>>>> I have checked "SMI woraround" for the kernel.
>>>> In BIOS I have UNchecked  "legacy usb".
>>>>
>>>>
>>>> my Desktop PC (a AMD ATHLON) can boot with this little vanilla kernel
>>>> and
>>>> 1/ a little embedded distrib of my own
>>>>
>>>> OR
>>>>
>>>> 2/ a complete mandrake 9.1 on a partition of a classic hard disk
>>>>
>>>> I have 2 differents problems when I lauch this :
>>>>
>>>> 1/ with the linux embedded directories on the usb key
>>>> high latency > 100 us are ok ? perhaps usb work is not compatible
>>>> with RT ?
>>>>     
>>>>         
>>> Try loading the standard USB drivers (at least uhci_hcd) if they aren't
>>> yet. Actually, I've seen boxes (granted, they were far older) where I
>>> had to switch legacy USB *on* to avoid disturbances. In any case, check
>>> carefully if you followed all tips in TROUBLESHOOTING regarding latency
>>> issues (APM, ACPI, etc.).
>>>
>>>  
>>>       
>>>> 2/ with the complete mandrake 9.1 :
>>>> it crashes X after 1 or few minutes.
>>>> What is the relation between X and Xenomai ?
>>>> Is Xenomai compatible with X ?
>>>>     
>>>>         
>>> Yes, as long as X is not playing against us, e.g. by hard-disabling
>>> interrupts or doing (too) evil things on the buses. Any non-GPL driver
>>> in this game here (NVidia&Co)? Better avoid this. Also try to disable
>>> accelerated mode in your X setup to see if things improve.
>>>
>>> Jan
>>>
>>>   
>>>       
>> Ok , for the box with a vanilla kernel I will try the differents
>> possibilities. Actually i disable
>> a max of things ...
>>
>> For the box with X : the big surprise was : very goods latencies
>> (comparativeley with no X !!)
>> Why ????
>> (Before crashing)
>>     
>
> If it turns out to be an ACPI/APM issue, X may keep your box busier than
> plain text mode, thus avoid those latency peaks by keeping it out of
> certain sleep modes - well, an attempt to explain something I can't with
> the currently available information...
>
>   
>> for crashing
>> I 'll verify theses 2 points :
>> nvidia driver
>> accelerated mode  : Is it a x server setup ?
>>
>>     
>
> See Gilles' reply => XF86Config.
>
> Jan
>
>
> PS: Don't forget to reply-to-all.
>
>   
OK !

	

	
		
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