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 <[email protected]> > 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 > > [email protected] > > https://mail.gna.org/listinfo/xenomai-help > > -- > Philippe. > > > > > > -- > Thanks and regards > Bharath > -- Philippe. _______________________________________________ Xenomai-help mailing list [email protected] https://mail.gna.org/listinfo/xenomai-help
