Kernel code interrupted by Timer

[anish kumar]

On Sun, 2013-02-10 at 00:47 +0800, Peter Teoh wrote:
> 
> 
> On Sun, Feb 10, 2013 at 12:22 AM, Frederic Weisbecker
> <fweisbec at gmail.com> wrote:
>         2013/2/9 Peter Teoh <htmldeveloper at gmail.com>:
>         > A search in the entire subtree of arch/x86/ and including
>         all its
>         > subdirectories, (for 3.2.0 kernel) return only TWO result
>         where
>         > preempt_schedule_irq is called:   kernel/entry_64.S and
>         kernel/entry_32.S.
>         > And the called is in fact resume_kernel(),   ie, it is NOT
>         called from timer
>         > interrupt, but from wakeup context of the CPU, and is only
>         executed ONCE
>         > upon waking up from hibernation.
>         >
>         > for example, calling from here:
>         >
>         > https://lkml.org/lkml/2012/5/2/298
>         >
>         > so definitely this preempt_schedule_irq() calling from irq
>         mode is rare - at
>         > least for x86.
>         
>         
>         The name "resume_kernel" can indeed sound like something that
>         is
>         called on hibernation resume. It's actually not related at
>         all. It's a
>         piece of code that is called at the end of every irq and
>         exception
>         when the interrupted code was running in the kernel. If the
>         interrupted code was running in userspace, we jump to
>         resume_userspace.
> 
> well, i guessed u must be the expert here, i have yet to really digest
> all these...:-).   thanks for the explanation.
In the kernel folder do this:
git log --author="Frederic Weisbecker"
> 
> 
> -- 
> Regards,
> Peter Teoh