Preemptive Kernel and MPC8xx ???

Preemptive Kernel and MPC8xx ???

[Steven Scholz]

Hi there,

is somebody actually using the preemptive kernel patches that can be found at

http://www.kernel.org/pub/linux/kernel/people/rml/preempt-kernel/v2.4/

on MPC8xx boards?

If so which kernel version?

Thanks a million!

Steven


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Re: Preemptive Kernel and MPC8xx ???

[Jaap-Jan Boor]

Hi,

Yes I do on 2.4.20 and 2.4.22 from kernel.org. So far all seems
to work but didn't do any measurements on it.
(I both use the preempt and low-latency patches)

Jaap-Jan

On 23-nov-03, at 13:02, Steven Scholz wrote:

>
> Hi there,
>
> is somebody actually using the preemptive kernel patches that can be
> found at
>
> http://www.kernel.org/pub/linux/kernel/people/rml/preempt-kernel/v2.4/
>
> on MPC8xx boards?
>
> If so which kernel version?
>
> Thanks a million!
>
> Steven
>
>


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Re: Preemptive Kernel and MPC8xx ???

[Steven Scholz]

Hi,

>> is somebody actually using the preemptive kernel patches ...
>>
> Yes I do on 2.4.20 and 2.4.22 from kernel.org. So far all seems
> to work but didn't do any measurements on it.
So you're using vanilla 2.4.22 on your MPC8xx board!?

> (I both use the preempt and low-latency patches)
Sound interessting.
Could you please give me a link to find the mentioned "low-latency patches".

Thanks,

Steven


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Re: Preemptive Kernel and MPC8xx ???

[Jaap-Jan Boor]

On Mon, 2003-11-24 at 09:01, Steven Scholz wrote:
> Hi,
>
> >> is somebody actually using the preemptive kernel patches ...
> >>
> > Yes I do on 2.4.20 and 2.4.22 from kernel.org. So far all seems
> > to work but didn't do any measurements on it.
> So you're using vanilla 2.4.22 on your MPC8xx board!?

yes, am I stupid?

Currently I use smc uart, scc ethernet and a modified
cpm_spi driver (from the great Denx) with interrupt handling,
my 850 board boots ok from nfsroot

>
> > (I both use the preempt and low-latency patches)
> Sound interessting.
> Could you please give me a link to find the mentioned "low-latency patches".

it comes from Andrew Morton's page
http://www.zip.com.au/~akpm/linux/schedlat.html

I you have to enable this by hand in arch/ppc/config.in (look at
arch/i386/config.in) with

bool 'Low latency scheduling' CONFIG_LOLAT
dep_bool 'Control low latency with sysctl' CONFIG_LOLAT_SYSCTL
$CONFIG_LOLAT

>
> Thanks,
>
> Steven


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Re: Preemptive Kernel and MPC8xx ???

[Steven Scholz]

Hi,m

>>>>is somebody actually using the preemptive kernel patches ...
>>>
>>>Yes I do on 2.4.20 and 2.4.22 from kernel.org. So far all seems
>>>to work but didn't do any measurements on it.
>>
>>So you're using vanilla 2.4.22 on your MPC8xx board!?
>
> yes, am I stupid?

NO! I nerver said that!
I just didn't know that vanilla 2.4.22 from kernel.org is now stable enough
w.r.t. MPC8xx.

>>Could you please give me a link to find the mentioned "low-latency patches".
>
> it comes from Andrew Morton's page
> http://www.zip.com.au/~akpm/linux/schedlat.html
Thanks a million.

Good luck,

Steven


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Re: Preemptive Kernel and MPC8xx ???

[Marius Groeger]

On Mon, 24 Nov 2003, Jaap-Jan Boor wrote:

> Yes I do on 2.4.20 and 2.4.22 from kernel.org. So far all seems
> to work but didn't do any measurements on it.
> (I both use the preempt and low-latency patches)

AFAIK, you can pretty much drop the low-latency patch in favor of
using the lock-breaking patch. It is also available from Robert Love
at the cited home page.

Marius

--
Marius Groeger <mgroeger@sysgo.de>
Project Manager

SYSGO Real-Time Solutions AG | Embedded and Real-Time Software
Am Pfaffenstein 14
55270 Klein-Winternheim, Germany

Voice: +49-6136-9948-0 | FAX: +49-6136-9948-10
www.sysgo.de | www.elinos.com | www.osek.de

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Re: Preemptive Kernel and MPC8xx ???

[Jaap-Jan Boor]

On 24-nov-03, at 17:35, Marius Groeger wrote:

>
> On Mon, 24 Nov 2003, Jaap-Jan Boor wrote:
>
>> Yes I do on 2.4.20 and 2.4.22 from kernel.org. So far all seems
>> to work but didn't do any measurements on it.
>> (I both use the preempt and low-latency patches)
>
> AFAIK, you can pretty much drop the low-latency patch in favor of
> using the lock-breaking patch. It is also available from Robert Love
> at the cited home page.

Yes, thanks, I know.
Is it better? I thought both low-latency and lock-break
do more or less the same.

Jaap-Jan


>
> Marius
>
> --
> Marius Groeger <mgroeger@sysgo.de>
> Project Manager
>
> SYSGO Real-Time Solutions AG | Embedded and Real-Time Software
> Am Pfaffenstein 14
> 55270 Klein-Winternheim, Germany
>
> Voice: +49-6136-9948-0 | FAX: +49-6136-9948-10
> www.sysgo.de | www.elinos.com | www.osek.de
>


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Re: Preemptive Kernel and MPC8xx ???

[Steven Scholz]

Hi,

> On Mon, 24 Nov 2003, Jaap-Jan Boor wrote:
>
>>Yes I do on 2.4.20 and 2.4.22 from kernel.org. So far all seems
>>to work but didn't do any measurements on it.
>>(I both use the preempt and low-latency patches)
Have you writting your own device drivers?
How did you make them preemptable?

Marius Groeger wrote:
> AFAIK, you can pretty much drop the low-latency patch in favor of
> using the lock-breaking patch. It is also available from Robert Love
> at the cited home page.
How about homemade device drivers when using the lock-breaking patch?

Thanks!

--
Steven Scholz

imc Measurement & Control               imc Meßsysteme GmbH
Voltastr. 5                             Voltastr. 5
13355 Berlin                            13355 Berlin
Germany                                 Deutschland
fon: +49 30 467090-0                    Tel: 030 / 467090-0
fax: +49 30 4631576                     fax: 030 / 4631576


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Re: Preemptive Kernel and MPC8xx ???

[Steven Scholz]

Marius Groeger wrote:

> AFAIK, you can pretty much drop the low-latency patch in favor of
> using the lock-breaking patch. It is also available from Robert Love
> at the cited home page.

Rob Love wrote me:

 >>Is it correct that your lock-break does basicly the same as Andrew Morton's
 >>low-latency patches? Where is the big difference?
 >
 > Yes, basically the same thing.  Lock-break is a version of low-latency
 > that is "optimized" for use with the preemptive kernel.
 >
 > You might as well just use low-latency, as Andrew is keeping that more
 > up to date.

And that's what I noticed when looking and the download pages...

That leaves three options:

 > 	(a) Use only preempt-kernel
 > 	(b) Use only low-latency
 > 	(c) Use preempt-kernel + low-latency

Right?

--
Steven Scholz

imc Measurement & Control               imc Meßsysteme GmbH
Voltastr. 5                             Voltastr. 5
13355 Berlin                            13355 Berlin
Germany                                 Deutschland
fon: +49 30 467090-0                    Tel: 030 / 467090-0
fax: +49 30 4631576                     fax: 030 / 4631576


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Re: Preemptive Kernel and MPC8xx ???

[Jaap-Jan Boor]

On Tue, 2003-11-25 at 09:13, Steven Scholz wrote:
> Hi,
>
> > On Mon, 24 Nov 2003, Jaap-Jan Boor wrote:
> >
> >>Yes I do on 2.4.20 and 2.4.22 from kernel.org. So far all seems
> >>to work but didn't do any measurements on it.
> >>(I both use the preempt and low-latency patches)
> Have you writting your own device drivers?
> How did you make them preemptable?

I didn't... I still assume the kernel will lock
e.g. the same SIU irq

>
> Marius Groeger wrote:
> > AFAIK, you can pretty much drop the low-latency patch in favor of
> > using the lock-breaking patch. It is also available from Robert Love
> > at the cited home page.
> How about homemade device drivers when using the lock-breaking patch?
>
> Thanks!
>
> --
> Steven Scholz
>
> imc Measurement & Control               imc Meßsysteme GmbH
> Voltastr. 5                             Voltastr. 5
> 13355 Berlin                            13355 Berlin
> Germany                                 Deutschland
> fon: +49 30 467090-0                    Tel: 030 / 467090-0
> fax: +49 30 4631576                     fax: 030 / 4631576
>
>


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Re: Preemptive Kernel and MPC8xx ???

[Jaap-Jan Boor]

On Wed, 2003-11-26 at 16:08, Steven Scholz wrote:
> Marius Groeger wrote:
>
> > AFAIK, you can pretty much drop the low-latency patch in favor of
> > using the lock-breaking patch. It is also available from Robert Love
> > at the cited home page.
>
> Rob Love wrote me:
>
>  >>Is it correct that your lock-break does basicly the same as Andrew Morton's
>  >>low-latency patches? Where is the big difference?
>  >
>  > Yes, basically the same thing.  Lock-break is a version of low-latency
>  > that is "optimized" for use with the preemptive kernel.
>  >
>  > You might as well just use low-latency, as Andrew is keeping that more
>  > up to date.
>
> And that's what I noticed when looking and the download pages...
>
> That leaves three options:
>
>  > 	(a) Use only preempt-kernel
>  > 	(b) Use only low-latency
>  > 	(c) Use preempt-kernel + low-latency
>
> Right?

Yes, I use (c)


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