Kernel threads and system usage metric.

[Daniel Hilst]

On 03/09/2012 06:25 PM, Mulyadi Santosa wrote:
> Hi :)
>
> On Fri, Mar 9, 2012 at 18:39, Daniel Hilst<danielhilst at gmail.com>  wrote:
>> The processes that appear in top with brackets are the kernel threads?
>
> Yup :)
>
>> If so, this threads spend all its time on system mode, right?
>
> Yes, it supposed to ...
>
>> By the
>> system mode I mean the %sy on top header, since kernel threads hasn't
>> any memory mapped to user space, it can't run on user space at any time,
>> right?
>
> IIRC, kernel thread simply "borrow" any previous scheduled task's
> address space. In that matter, it also has user address space. So, if
> wanted, kernel thread could access user space. But normally it doesn't
> do it.
>
>>
>>
>> So the total of system mode usage is the sum of all processes processing
>> in kernel space, plus the kernel threads processing, right?
>
> remember that kernel threads are also processes, so no need to
> differentiate between normal processes and kernel threads, especially
> when we talk about CPU utilization.
>
Thanks Mulyadi!

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