Kernel threads and system usage metric.
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!
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
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!
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
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participants (3)
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Chetan Nanda -
Daniel Hilst -
Mulyadi Santosa