Kernel threads and system usage metric.

Kernel threads and system usage metric.

[Daniel Hilst]

Doubt!

The processes that appear in top with brackets are the kernel threads?

If so, this threads spend all its time on system mode, right? 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?


So the total of system mode usage is the sum of all processes processing 
in kernel space, plus the kernel threads processing, right?

Thanks in advance!

-- 
Follow the white rabbit!

Kernel threads and system usage metric.

[Mulyadi Santosa]

Hi :)

On Fri, Mar 9, 2012 at 18:39, Daniel Hilst <danielhilst@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.

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

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

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@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!

-- 
Follow the white rabbit!

Kernel threads and system usage metric.

[Chetan Nanda]

On Mar 9, 2012 11:57 PM, "Mulyadi Santosa" <mulyadi.santosa@gmail.com>
wrote:
>
> Hi :)
>
> On Fri, Mar 9, 2012 at 18:39, Daniel Hilst <danielhilst@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.
>
AFAIK kernel threads do not have any userspace context. As it is never
gaurnted which userspace process was previously running when kernel thread
scheduled to run.

> >
> >
> > 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.
>
> --
> regards,
>
> Mulyadi Santosa
> Freelance Linux trainer and consultant
>
> blog: the-hydra.blogspot.com
> training: mulyaditraining.blogspot.com
>
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
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