* [Xenomai-help] Page-fault, switch to secondary mode
@ 2010-08-25 9:12 Bharath Achuta Bhat
2010-08-25 9:42 ` Gilles Chanteperdrix
2010-08-25 9:53 ` Philippe Gerum
0 siblings, 2 replies; 7+ messages in thread
From: Bharath Achuta Bhat @ 2010-08-25 9:12 UTC (permalink / raw)
To: xenomai
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Hello Xenomai experts,
I am running a xenomai-2.5.1 patched kernel (v 2.6.30.3) with ipipe
version 2.7-06.
The target is powerpc (MPC8533E).
My application is switching to the secondary mode (I guess because of a
page-fault) when ntohl() is called.
This is a libc function and I am wondering why only this function (ntohl())
is causing a page-fault.
Here is how the application looks like
main ()
{
...
...
/* Avoids memory swapping for this program */
mlockall(MCL_CURRENT | MCL_FUTURE);
......
......
/* signal handlers */
.....
.....
/* create communication pipes */
rt_pipe_create(&tPipe1, .....
rt_pipe_create(&tPipe2,.......
/* create RT tasks */
rt_task_create(&tTask1,.....
rt_task_create(&tTask2,......
...........
..........
/* start the RT tasks */
rt_task_start(&tTask1,.....
..............
..............
/* turn the current thread into RT function */
ret = rt_task_shadow(NULL, "RT main function", 1, T_SUSP);
....
....
}
One of the rt tasks created calls ntohl() and switches to secondary mode.
Is there a way to avoid it ?
--
Thanks and regards
Bharath
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^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [Xenomai-help] Page-fault, switch to secondary mode
2010-08-25 9:12 [Xenomai-help] Page-fault, switch to secondary mode Bharath Achuta Bhat
@ 2010-08-25 9:42 ` Gilles Chanteperdrix
2010-08-25 9:53 ` Philippe Gerum
1 sibling, 0 replies; 7+ messages in thread
From: Gilles Chanteperdrix @ 2010-08-25 9:42 UTC (permalink / raw)
To: Bharath Achuta Bhat; +Cc: xenomai
Bharath Achuta Bhat wrote:
> Hello Xenomai experts,
>
> I am running a xenomai-2.5.1 patched kernel (v 2.6.30.3) with ipipe
> version 2.7-06.
> The target is powerpc (MPC8533E).
> My application is switching to the secondary mode (I guess because of a
> page-fault) when ntohl() is called.
> This is a libc function and I am wondering why only this function (ntohl())
> is causing a page-fault.
Before anything, could you try xenomai 2.5.3 ?
--
Gilles.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Xenomai-help] Page-fault, switch to secondary mode
2010-08-25 9:12 [Xenomai-help] Page-fault, switch to secondary mode Bharath Achuta Bhat
2010-08-25 9:42 ` Gilles Chanteperdrix
@ 2010-08-25 9:53 ` Philippe Gerum
2010-08-25 9:59 ` Gilles Chanteperdrix
2010-08-25 10:06 ` Bharath Achuta Bhat
1 sibling, 2 replies; 7+ messages in thread
From: Philippe Gerum @ 2010-08-25 9:53 UTC (permalink / raw)
To: Bharath Achuta Bhat; +Cc: xenomai
On Wed, 2010-08-25 at 11:12 +0200, Bharath Achuta Bhat wrote:
> Hello Xenomai experts,
>
>
> I am running a xenomai-2.5.1 patched kernel (v 2.6.30.3) with ipipe
> version 2.7-06.
> The target is powerpc (MPC8533E).
> My application is switching to the secondary mode (I guess because of
> a page-fault) when ntohl() is called.
> This is a libc function and I am wondering why only this function
> (ntohl()) is causing a page-fault.
What memory are you reading from / writing to in the statement involving
ntohl()? Is this plain RAM, or mapped I/O memory?
>
>
> Here is how the application looks like
>
>
> main ()
> {
> ...
> ...
> /* Avoids memory swapping for this program */
> mlockall(MCL_CURRENT | MCL_FUTURE);
>
>
> ......
> ......
> /* signal handlers */
> .....
> .....
> /* create communication pipes */
> rt_pipe_create(&tPipe1, .....
> rt_pipe_create(&tPipe2,.......
>
>
> /* create RT tasks */
> rt_task_create(&tTask1,.....
> rt_task_create(&tTask2,......
> ...........
> ..........
>
>
> /* start the RT tasks */
> rt_task_start(&tTask1,.....
> ..............
> ..............
>
>
> /* turn the current thread into RT function */
> ret = rt_task_shadow(NULL, "RT main function", 1, T_SUSP);
>
>
> ....
> ....
>
>
> }
>
>
> One of the rt tasks created calls ntohl() and switches to secondary
> mode.
> Is there a way to avoid it ?
>
>
> --
> Thanks and regards
> Bharath
>
> _______________________________________________
> Xenomai-help mailing list
> Xenomai-help@domain.hid
> https://mail.gna.org/listinfo/xenomai-help
--
Philippe.
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [Xenomai-help] Page-fault, switch to secondary mode
2010-08-25 9:53 ` Philippe Gerum
@ 2010-08-25 9:59 ` Gilles Chanteperdrix
2010-08-25 10:06 ` Bharath Achuta Bhat
1 sibling, 0 replies; 7+ messages in thread
From: Gilles Chanteperdrix @ 2010-08-25 9:59 UTC (permalink / raw)
To: Philippe Gerum; +Cc: Bharath Achuta Bhat, xenomai
Philippe Gerum wrote:
> On Wed, 2010-08-25 at 11:12 +0200, Bharath Achuta Bhat wrote:
>> Hello Xenomai experts,
>>
>>
>> I am running a xenomai-2.5.1 patched kernel (v 2.6.30.3) with ipipe
>> version 2.7-06.
>> The target is powerpc (MPC8533E).
>> My application is switching to the secondary mode (I guess because of
>> a page-fault) when ntohl() is called.
>> This is a libc function and I am wondering why only this function
>> (ntohl()) is causing a page-fault.
>
> What memory are you reading from / writing to in the statement involving
> ntohl()? Is this plain RAM, or mapped I/O memory?
And if it is plain RAM, is it correctly aligned?
--
Gilles.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Xenomai-help] Page-fault, switch to secondary mode
2010-08-25 9:53 ` Philippe Gerum
2010-08-25 9:59 ` Gilles Chanteperdrix
@ 2010-08-25 10:06 ` Bharath Achuta Bhat
2010-08-25 14:22 ` Philippe Gerum
1 sibling, 1 reply; 7+ messages in thread
From: Bharath Achuta Bhat @ 2010-08-25 10:06 UTC (permalink / raw)
To: Philippe Gerum; +Cc: xenomai
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Hi Philippe,
It is an mmap-ed I/O memory.
Regards
Bharath
On Wed, Aug 25, 2010 at 11:53 AM, Philippe Gerum <rpm@xenomai.org> wrote:
> On Wed, 2010-08-25 at 11:12 +0200, Bharath Achuta Bhat wrote:
> > Hello Xenomai experts,
> >
> >
> > I am running a xenomai-2.5.1 patched kernel (v 2.6.30.3) with ipipe
> > version 2.7-06.
> > The target is powerpc (MPC8533E).
> > My application is switching to the secondary mode (I guess because of
> > a page-fault) when ntohl() is called.
> > This is a libc function and I am wondering why only this function
> > (ntohl()) is causing a page-fault.
>
> What memory are you reading from / writing to in the statement involving
> ntohl()? Is this plain RAM, or mapped I/O memory?
>
> >
> >
> > Here is how the application looks like
> >
> >
> > main ()
> > {
> > ...
> > ...
> > /* Avoids memory swapping for this program */
> > mlockall(MCL_CURRENT | MCL_FUTURE);
> >
> >
> > ......
> > ......
> > /* signal handlers */
> > .....
> > .....
> > /* create communication pipes */
> > rt_pipe_create(&tPipe1, .....
> > rt_pipe_create(&tPipe2,.......
> >
> >
> > /* create RT tasks */
> > rt_task_create(&tTask1,.....
> > rt_task_create(&tTask2,......
> > ...........
> > ..........
> >
> >
> > /* start the RT tasks */
> > rt_task_start(&tTask1,.....
> > ..............
> > ..............
> >
> >
> > /* turn the current thread into RT function */
> > ret = rt_task_shadow(NULL, "RT main function", 1, T_SUSP);
> >
> >
> > ....
> > ....
> >
> >
> > }
> >
> >
> > One of the rt tasks created calls ntohl() and switches to secondary
> > mode.
> > Is there a way to avoid it ?
> >
> >
> > --
> > Thanks and regards
> > Bharath
> >
> > _______________________________________________
> > Xenomai-help mailing list
> > Xenomai-help@domain.hid
> > https://mail.gna.org/listinfo/xenomai-help
>
> --
> Philippe.
>
>
>
--
Thanks and regards
Bharath
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^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [Xenomai-help] Page-fault, switch to secondary mode
2010-08-25 10:06 ` Bharath Achuta Bhat
@ 2010-08-25 14:22 ` Philippe Gerum
2010-08-26 7:20 ` Bharath Achuta Bhat
0 siblings, 1 reply; 7+ messages in thread
From: Philippe Gerum @ 2010-08-25 14:22 UTC (permalink / raw)
To: Bharath Achuta Bhat; +Cc: xenomai
On Wed, 2010-08-25 at 12:06 +0200, Bharath Achuta Bhat wrote:
> Hi Philippe,
> It is an mmap-ed I/O memory.
This is a TLB miss which ends up in a heavyweight call to fill the linux
page table entry. Try to pre-fault the I/O memory region if possible,
reading some bytes within the same 4k page.
>
>
> Regards
> Bharath
>
> On Wed, Aug 25, 2010 at 11:53 AM, Philippe Gerum <rpm@xenomai.org>
> wrote:
> On Wed, 2010-08-25 at 11:12 +0200, Bharath Achuta Bhat wrote:
> > Hello Xenomai experts,
> >
> >
> > I am running a xenomai-2.5.1 patched kernel (v 2.6.30.3)
> with ipipe
> > version 2.7-06.
> > The target is powerpc (MPC8533E).
> > My application is switching to the secondary mode (I guess
> because of
> > a page-fault) when ntohl() is called.
> > This is a libc function and I am wondering why only this
> function
> > (ntohl()) is causing a page-fault.
>
>
> What memory are you reading from / writing to in the statement
> involving
> ntohl()? Is this plain RAM, or mapped I/O memory?
>
> >
> >
> > Here is how the application looks like
> >
> >
> > main ()
> > {
> > ...
> > ...
> > /* Avoids memory swapping for this program */
> > mlockall(MCL_CURRENT | MCL_FUTURE);
> >
> >
> > ......
> > ......
> > /* signal handlers */
> > .....
> > .....
> > /* create communication pipes */
> > rt_pipe_create(&tPipe1, .....
> > rt_pipe_create(&tPipe2,.......
> >
> >
> > /* create RT tasks */
> > rt_task_create(&tTask1,.....
> > rt_task_create(&tTask2,......
> > ...........
> > ..........
> >
> >
> > /* start the RT tasks */
> > rt_task_start(&tTask1,.....
> > ..............
> > ..............
> >
> >
> > /* turn the current thread into RT function */
> > ret = rt_task_shadow(NULL, "RT main function", 1, T_SUSP);
> >
> >
> > ....
> > ....
> >
> >
> > }
> >
> >
> > One of the rt tasks created calls ntohl() and switches to
> secondary
> > mode.
> > Is there a way to avoid it ?
> >
> >
> > --
> > Thanks and regards
> > Bharath
> >
>
> > _______________________________________________
> > Xenomai-help mailing list
> > Xenomai-help@domain.hid
> > https://mail.gna.org/listinfo/xenomai-help
>
> --
> Philippe.
>
>
>
>
>
> --
> Thanks and regards
> Bharath
>
--
Philippe.
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [Xenomai-help] Page-fault, switch to secondary mode
2010-08-25 14:22 ` Philippe Gerum
@ 2010-08-26 7:20 ` Bharath Achuta Bhat
0 siblings, 0 replies; 7+ messages in thread
From: Bharath Achuta Bhat @ 2010-08-26 7:20 UTC (permalink / raw)
To: Philippe Gerum; +Cc: xenomai
[-- Attachment #1: Type: text/plain, Size: 3256 bytes --]
Hi Philippe,
Thank you for the suggestion. I will give it a try and let you know.
Regards
Bharath
On Wed, Aug 25, 2010 at 4:22 PM, Philippe Gerum <rpm@xenomai.org> wrote:
> On Wed, 2010-08-25 at 12:06 +0200, Bharath Achuta Bhat wrote:
> > Hi Philippe,
> > It is an mmap-ed I/O memory.
>
> This is a TLB miss which ends up in a heavyweight call to fill the linux
> page table entry. Try to pre-fault the I/O memory region if possible,
> reading some bytes within the same 4k page.
>
> >
> >
> > Regards
> > Bharath
> >
> > On Wed, Aug 25, 2010 at 11:53 AM, Philippe Gerum <rpm@xenomai.org>
> > wrote:
> > On Wed, 2010-08-25 at 11:12 +0200, Bharath Achuta Bhat wrote:
> > > Hello Xenomai experts,
> > >
> > >
> > > I am running a xenomai-2.5.1 patched kernel (v 2.6.30.3)
> > with ipipe
> > > version 2.7-06.
> > > The target is powerpc (MPC8533E).
> > > My application is switching to the secondary mode (I guess
> > because of
> > > a page-fault) when ntohl() is called.
> > > This is a libc function and I am wondering why only this
> > function
> > > (ntohl()) is causing a page-fault.
> >
> >
> > What memory are you reading from / writing to in the statement
> > involving
> > ntohl()? Is this plain RAM, or mapped I/O memory?
> >
> > >
> > >
> > > Here is how the application looks like
> > >
> > >
> > > main ()
> > > {
> > > ...
> > > ...
> > > /* Avoids memory swapping for this program */
> > > mlockall(MCL_CURRENT | MCL_FUTURE);
> > >
> > >
> > > ......
> > > ......
> > > /* signal handlers */
> > > .....
> > > .....
> > > /* create communication pipes */
> > > rt_pipe_create(&tPipe1, .....
> > > rt_pipe_create(&tPipe2,.......
> > >
> > >
> > > /* create RT tasks */
> > > rt_task_create(&tTask1,.....
> > > rt_task_create(&tTask2,......
> > > ...........
> > > ..........
> > >
> > >
> > > /* start the RT tasks */
> > > rt_task_start(&tTask1,.....
> > > ..............
> > > ..............
> > >
> > >
> > > /* turn the current thread into RT function */
> > > ret = rt_task_shadow(NULL, "RT main function", 1, T_SUSP);
> > >
> > >
> > > ....
> > > ....
> > >
> > >
> > > }
> > >
> > >
> > > One of the rt tasks created calls ntohl() and switches to
> > secondary
> > > mode.
> > > Is there a way to avoid it ?
> > >
> > >
> > > --
> > > Thanks and regards
> > > Bharath
> > >
> >
> > > _______________________________________________
> > > Xenomai-help mailing list
> > > Xenomai-help@domain.hid
> > > https://mail.gna.org/listinfo/xenomai-help
> >
> > --
> > Philippe.
> >
> >
> >
> >
> >
> > --
> > Thanks and regards
> > Bharath
> >
>
> --
> Philippe.
>
>
>
--
Thanks and regards
Bharath
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^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2010-08-26 7:20 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2010-08-25 9:12 [Xenomai-help] Page-fault, switch to secondary mode Bharath Achuta Bhat
2010-08-25 9:42 ` Gilles Chanteperdrix
2010-08-25 9:53 ` Philippe Gerum
2010-08-25 9:59 ` Gilles Chanteperdrix
2010-08-25 10:06 ` Bharath Achuta Bhat
2010-08-25 14:22 ` Philippe Gerum
2010-08-26 7:20 ` Bharath Achuta Bhat
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