RT example

RT example

[Junior]

Hi All,
Does anyone have example code using the PREEMPT_RT patch?

I've installed the patch for 2.6.18 and notice I'm actually runiing slower that without the patch.
I'm pretty sure it's something I'm doing or not doing and an example or some other docs should be enough to get me started.

Thanks,
PS. I'm using an ARM9 platform 

Re: RT example

[Robert Schwebel]

On Wed, Jan 24, 2007 at 10:58:41AM -0800, Junior wrote:
> Does anyone have example code using the PREEMPT_RT patch?

You could for example start with cyclictest. It is also a good example
for how to write cyclic realtime programs on Linux.

> I've installed the patch for 2.6.18 and notice I'm actually runiing
> slower that without the patch.  I'm pretty sure it's something I'm
> doing or not doing and an example or some other docs should be enough
> to get me started.

Note that realtime is not about running fast, but running "in time".
That may often mean that the overall system performance goes down.

> PS. I'm using an ARM9 platform 

Do you have clocksource/clockevent support for your ARM9 chip?

Robert
-- 
 Dipl.-Ing. Robert Schwebel | http://www.pengutronix.de
 Pengutronix - Linux Solutions for Science and Industry
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     Hannoversche Str. 2, 31134 Hildesheim, Germany
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Re: RT example

[Junior]

> On Wed, Jan 24, 2007 at 10:58:41AM -0800, Junior wrote:
>> Does anyone have example code using the PREEMPT_RT patch?
> 
> You could for example start with cyclictest. It is also a good example
> for how to write cyclic realtime programs on Linux.

Thanks, I will start there.

> Note that realtime is not about running fast, but running "in time".
> That may often mean that the overall system performance goes down.
> 
>> PS. I'm using an ARM9 platform
> 
> Do you have clocksource/clockevent support for your ARM9 chip?

Aparently I don't. It's set as IS_TICK_BASED. How does this affect the system?

Thanks,
--Jr.

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Re: RT example

[Junior]

> On Wed, Jan 24, 2007 at 10:58:41AM -0800, Junior wrote:
>> Does anyone have example code using the PREEMPT_RT patch?
> 
> You could for example start with cyclictest. It is also a good example
> for how to write cyclic realtime programs on Linux.

Thanks, I will start there.

Where do I get the rt library? (-lrt in makefile)?

cyclictest.c: In function `timerthread':
cyclictest.c:153: error: `SIGEV_THREAD_ID' undeclared (first use in this function)

Someone got this before but no solution on how to fix it.


> Note that realtime is not about running fast, but running "in time".
> That may often mean that the overall system performance goes down.
> 
>> PS. I'm using an ARM9 platform
> 
> Do you have clocksource/clockevent support for your ARM9 chip?

Aparently I don't. It's set as IS_TICK_BASED. How does this affect the system?

Thanks,
--Jr.

Re: RT example

[Junior]

Hi All,
Does anyone have any comments on my quesions below.
I'm really looking for a good place to start and it would be a great help  if someone could suggest one.

Or, someone could guide me in the right direction with a serial driver I'm working on. I'm trying to make the serial driver interrupt
get serviced with 10-12ms when its fired. Do I use a timer or is there something in the rt patch that I can adjust in response to interrupts?

Thanks much.
--Junior

> -----Original Message-----
> From: ejr@inbox.com
> Sent: Thu, 25 Jan 2007 07:11:30 -0800
> To: r.schwebel@pengutronix.de
> Subject: Re: RT example
> 
>> On Wed, Jan 24, 2007 at 10:58:41AM -0800, Junior wrote:
>>> Does anyone have example code using the PREEMPT_RT patch?
>> 
>> You could for example start with cyclictest. It is also a good example
>> for how to write cyclic realtime programs on Linux.
> 
> Thanks, I will start there.
> 
> Where do I get the rt library? (-lrt in makefile)?
> 
> cyclictest.c: In function `timerthread':
> cyclictest.c:153: error: `SIGEV_THREAD_ID' undeclared (first use in this
> function)
> 
> Someone got this before but no solution on how to fix it.
> 
> 
>> Note that realtime is not about running fast, but running "in time".
>> That may often mean that the overall system performance goes down.
>> 
>>> PS. I'm using an ARM9 platform
>> 
>> Do you have clocksource/clockevent support for your ARM9 chip?
> 
> Aparently I don't. It's set as IS_TICK_BASED. How does this affect the
> system?
> 
> Thanks,
> --Jr.
> 

Re: RT example

[Junior]

With no response, perhaps someone can tell me what are the basic needs for a ARM platform to use the rt patches.
So far, the pactches hurt rather than help me and I've remove them. So, there must be something I don't know I'm missing.

Your help will be appreciated.
--Jr.


> -----Original Message-----
> From: ejr@inbox.com
> Sent: Sat, 27 Jan 2007 11:34:05 -0800
> To: ejr@inbox.com, r.schwebel@pengutronix.de
> Subject: Re: RT example
> 
> Hi All,
> Does anyone have any comments on my quesions below.
> I'm really looking for a good place to start and it would be a great help
> if someone could suggest one.
> 
> Or, someone could guide me in the right direction with a serial driver
> I'm working on. I'm trying to make the serial driver interrupt
> get serviced with 10-12ms when its fired. Do I use a timer or is there
> something in the rt patch that I can adjust in response to interrupts?
> 
> Thanks much.
> --Junior
> 
>> -----Original Message-----
>> From: ejr@inbox.com
>> Sent: Thu, 25 Jan 2007 07:11:30 -0800
>> To: r.schwebel@pengutronix.de
>> Subject: Re: RT example
>> 
>>> On Wed, Jan 24, 2007 at 10:58:41AM -0800, Junior wrote:
>>>> Does anyone have example code using the PREEMPT_RT patch?
>>> 
>>> You could for example start with cyclictest. It is also a good example
>>> for how to write cyclic realtime programs on Linux.
>> 
>> Thanks, I will start there.
>> 
>> Where do I get the rt library? (-lrt in makefile)?
>> 
>> cyclictest.c: In function `timerthread':
>> cyclictest.c:153: error: `SIGEV_THREAD_ID' undeclared (first use in this
>> function)
>> 
>> Someone got this before but no solution on how to fix it.
>> 
>> 
>>> Note that realtime is not about running fast, but running "in time".
>>> That may often mean that the overall system performance goes down.
>>> 
>>>> PS. I'm using an ARM9 platform
>>> 
>>> Do you have clocksource/clockevent support for your ARM9 chip?
>> 
>> Aparently I don't. It's set as IS_TICK_BASED. How does this affect the
>> system?
>> 
>> Thanks,
>> --Jr.