On Wed, 2013-01-16 at 10:25 +0000, Anuz Pratap Singh Tomar wrote:

On Tue, Jan 15, 2013 at 6:31 AM, horseriver <horserivers@gmail.com> wrote: hi:

what is the function of do_softirq()?

Softirq is basically same as bottom half except it is run in irq context.So the question which comes to mind is why softirq?Softirqs can run concurrently on several CPUs and that is why it used in networking. There are other advantages also but it is mostly use case dependent.

It is called by ksoftirqd() ,which is setup by : kernel_thread(ksoftirqd, hcpu, CLONE_KERNEL) ;

ksoftirq is a saviour thread which takes up the execution of softirq if it finds out that softirq are executing one by one and thereby userspace is not being scheduled or none of other task is getting executed.As threads have low priority it lets other tasks run.

Please read "Understanding the Linux Kernel" Chapter on Interrupts and Section on Softirqs and tasklets. Page number 171(might be different in other editions) onwards.

thanks!

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On Wed, Jan 16, 2013 at 4:35 PM, shubham <kernel.shubham@gmail.com> wrote:

Hi All,

I want to know if we have some documentation of kernel which specifically shows function calls in kernel code (It might be in the form of flow charts).

I think we can use tools like doxygen. Is there any work going on this ?

This may be bit outdated http://www.makelinux.net/kernel_map/

Regards Shubham

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-- Thank you Warm Regards Anuz

I think a diagram of function calls would be too much to fit in a reasonable sized diagram. I'm aware of diagrams of network function calls, and they are already big. You can use linux cross referencing (lxr) websites to follow function calls or download lxr and build the same thing for your own source code. I think you can also google diagrams of different kernel subsystems to find useful diagrams. On Wed, Jan 16, 2013 at 8:35 AM, shubham <kernel.shubham@gmail.com> wrote:

Hi All,

I want to know if we have some documentation of kernel which specifically shows function calls in kernel code (It might be in the form of flow charts).

I think we can use tools like doxygen. Is there any work going on this ?

Regards Shubham

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