query regarding kernel daemon

Mulyadi Santosa mulyadi.santosa at gmail.com
Tue Apr 5 02:40:35 EDT 2011

On Mon, Apr 4, 2011 at 16:28, shubham sharma <shubham20006 at gmail.com> wrote:
> The problem I am facing is that when I enter the string the second time, the
> system stalls. I added some sleeps in the code and figured out that when the
> proc function wakes up the daemon, the system stalls.

Typical: you must be doing somekind of busy looping or block while
interrupt is down. And this matter a lot since what running here is
kernel thread/daemon, which operate entirely in kernel space i.e if it
blocks, then the entire OS stalls since most likely scheduling happen
during kernel to user mode transition or voluntarily.

So as a side watch, check the preemption model your kernel use... try
to avoid no preemption...and if you could, switch to full preemption
mode...in this mode, preemption could happen on interrupt-to-kernel
mode transition.


Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

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