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From: Ryan Wang on 8 Jun 2010 21:40
Hi all,

I'm new to kernel development, and I'm learning
ftrace recently. I have one question:
When to use ftrace, or in which cases ftrace can be
more efficient?

thanks,
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From: Steven Rostedt on 8 Jun 2010 22:50
On Wed, 2010-06-09 at 09:38 +0800, Ryan Wang wrote:
> Hi all,
>
> I'm new to kernel development, and I'm learning
> ftrace recently. I have one question:
> When to use ftrace, or in which cases ftrace can be
> more efficient?

I can't really answer these questions without knowing what you want to
do?

ftrace allows you to see what is happening inside the kernel. What would
you like to see?

-- Steve


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From: Ryan Wang on 9 Jun 2010 01:40
2010/6/9 Steven Rostedt <srostedt(a)redhat.com>:
> On Wed, 2010-06-09 at 09:38 +0800, Ryan Wang wrote:
>> Hi all,
>>
>> � � � �I'm new to kernel development, and I'm learning
>> ftrace recently. I have one question:
>> � � � �When to use ftrace, or in which cases ftrace can be
>> more efficient?
>
> I can't really answer these questions without knowing what you want to
> do?
>
> ftrace allows you to see what is happening inside the kernel. What would
> you like to see?
>
> -- Steve
>
>
>

I really want to know is the differences between ftrace and other kernel debug
tools such as kdump, kdb, etc.

thanks!
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From: Ryan Wang on 9 Jun 2010 04:20
2010/6/9 Neependra Khare <neependra.khare(a)gmail.com>:
>
>
> On Wed, Jun 9, 2010 at 11:02 AM, Ryan Wang <openspace.wang(a)gmail.com> wrote:
>>
>> I really want to know is the differences between ftrace and other kernel
>> debug
>> tools such as kdump, kdb, etc.
>
> Lets say you want to know what ext2/ext3/ext4 functions are called when you
> run mkdir command on ext2/ext3/ext4 mounted filesystem. Then you can trace
> each kernel function with ftrace.
>
> Articles on ftrace:-
> http://lwn.net/Articles/365835/
> http://lwn.net/Articles/366796/
>
> With kdump you get memory dump of currently running kernel and then you
> debug it.
> kdb will help you to debug the currently running kernel.
>
> I hope this clears some of your doubts.
>
> Regards,
> Neependra
>
>>
>> thanks!
>>
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>>
>
>

Seems ftrace is helpful to study the activities inside the kernel to me.
I wonder whether it can be useful to debug kernel bugs. And if so, will
you please give me some examples? Or so far it's mainly used for
observing the running status of kernel?

thanks,
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