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Date: Wed, 04 Jul 2012 15:33:21 +0200
From: Philippe Gerum <rpm@xenomai.org>
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Subject: Re: [Xenomai] Xenomai and normal linux application - Wait time with
 select() not reliable
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To: =?ISO-8859-1?Q?Jens_K=F6hler?= <jenskxxx@googlemail.com>
Cc: xenomai@xenomai.org

On 07/04/2012 01:45 PM, Jens K=F6hler wrote:
> The Xenomai application runs every 2ms for about 150 us and sends/
> receives an udp packet.Rtnet socket is used for udp communication.
>
> /proc/xenomai/stat:
>
> CPU	PID	MSW	CSW	PF	STAT		%CPU  NAME
>    0	0	0	272362	0	00500080	93.8  ROOT
>    0	0	0	13475	0	00000082	0.0  rtnet-stack
>    0	0	0	1	0	00000082	0.0  rtnet-rtpc
>    0	1843	1	11677	0	00300182	0.1  SgbmReceive
>    0	1844	1	67501	0	00300184	4.7  SgbmSend
>    0	1845	63111	63304	0	00300380	0.3  SgbmUserSpaceComm

This thread seems to be switching modes a lot. Does it do this=20
frequently? Each mode switch involves a task switch linux-wise.

>    0	1846	1	134963	0	00300184	0.5  SgbmTimer
>    0	0	0	67500	0	00000000	0.3  IRQ19: rteth0
>    0	0	0	298425	0	00000000	0.3  IRQ233: [timer]
>
> Application was ported from RTAI to Xenomai. With Rtai was never a
> problem with select.

Is it supposed to give us any hint?

>
> Jens
>
>
> 2012/7/4, Philippe Gerum <rpm@xenomai.org>:
>> On 07/04/2012 10:45 AM, Gilles Chanteperdrix wrote:
>>> On 07/04/2012 10:36 AM, Jens K=F6hler wrote:
>>>> Thank you for your response Gilles. I set thread to SCHED_FIFO policy
>>>> with chrt command, Prio 99. But there is no improvement. Also
>>>> nanosleep do not help. The kernel is 2.6.26. What could be reason that
>>>> kernel is not restart thread when time is over?
>>>
>>> It could be that the xenomai activity, if any, is running for long
>>> periods of time and causing linux ticks to be delayed. As usual, it
>>> would help if you could provide a self-contained test-case allowing us
>>> to reproduce the issue.
>>>
>>
>> /proc/xenomai/stat as well, in case the rt activity changes mode a lot.
>>
>> --
>> Philippe.
>>
>>
>>
>


--=20
Philippe.