How CFS work in Android? Difference from Linux
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Deborah
Mar 16, 2012, 9:38:57 AM3/16/12
to Android Linux Kernel Development
I am trying to get a better understanding on ANDROID CFS. I have some
doubt on scheduler's behavior.
The difference between Android scheduler and Linux scheduler
Scheduler
— 5 files — The Android kernel also contains slight changes to the
CPU
process scheduler and time-keeping algorithms. We don’t know the
history of these changes, and the impact was not evident based on a
cursory examination.
Do you know which are this files?
If I understand, Process.THREAD_PRIORITY_DEFAULT or
Process.THREAD_PRIORITY_BACKGROUND are 'nice' value. How does Android
convert 'nice' value in 'timeslice'?
What is the initial value of 'virtual runtime' in Android and how to
calculate?
In Android, is 'cgroups' use to define scheduling classes? The
following application states: (i) Foreground process - Critical
priority; (ii) Visible process and Service process - High priority;
(iii) Background process and Empty process - Low priority; are three
scheduling classes ?
Thanks in advance,
Deborah
doubt on scheduler's behavior.
The difference between Android scheduler and Linux scheduler
Scheduler
— 5 files — The Android kernel also contains slight changes to the
CPU
process scheduler and time-keeping algorithms. We don’t know the
history of these changes, and the impact was not evident based on a
cursory examination.
Do you know which are this files?
If I understand, Process.THREAD_PRIORITY_DEFAULT or
Process.THREAD_PRIORITY_BACKGROUND are 'nice' value. How does Android
convert 'nice' value in 'timeslice'?
What is the initial value of 'virtual runtime' in Android and how to
calculate?
In Android, is 'cgroups' use to define scheduling classes? The
following application states: (i) Foreground process - Critical
priority; (ii) Visible process and Service process - High priority;
(iii) Background process and Empty process - Low priority; are three
scheduling classes ?
Thanks in advance,
Deborah
Glenn Kasten
Mar 19, 2012, 11:21:27 AM3/19/12
to android...@googlegroups.com
Threads voluntarily assign themselves a nice priority within the permitted range, and activity manager assigns threads of an app process to an appropriate cpuctl cgroup.
Deborah
Mar 19, 2012, 1:22:20 PM3/19/12
to Android Linux Kernel Development
Glenn thanks for your reply! I'm really confused. Could you explain
how the CFS work?
Does it divide the CPU time into epochs?
In a single epoch, has every process a specified time quantum that is
computed at the beginning of each epoch?
If yes, is 'virtual runtime' set to zero in each epoch or is it an
approximated average?
Help please!!! :(
how the CFS work?
Does it divide the CPU time into epochs?
In a single epoch, has every process a specified time quantum that is
computed at the beginning of each epoch?
If yes, is 'virtual runtime' set to zero in each epoch or is it an
approximated average?
Help please!!! :(
Glenn Kasten
Mar 19, 2012, 9:43:20 PM3/19/12
to android...@googlegroups.com
I'm sorry but generic Linux is beyond the scope of this group. I suggest doing a web search for the specific topics you're interested in. However, here are a few links to help you get started:
Deborah
Mar 20, 2012, 8:46:21 AM3/20/12
to Android Linux Kernel Development
Thanks, but maybe the only solution is to read the source code!!!
Regards,
Deborah
On Mar 20, 2:43 am, Glenn Kasten <gkas...@android.com> wrote:
> I'm sorry but generic Linux is beyond the scope of this group. I suggest
> doing a web search for the specific topics you're interested in. However,
> here are a few links to help you get started:
> http://en.wikipedia.org/wiki/Completely_Fair_Scheduler
> http://www.ibm.com/developerworks/linux/library/l-completely-fair-sch...
Regards,
Deborah
On Mar 20, 2:43 am, Glenn Kasten <gkas...@android.com> wrote:
> I'm sorry but generic Linux is beyond the scope of this group. I suggest
> doing a web search for the specific topics you're interested in. However,
> here are a few links to help you get started:
> http://en.wikipedia.org/wiki/Completely_Fair_Scheduler
San Mehat
Mar 20, 2012, 9:35:02 AM3/20/12
to android...@googlegroups.com
On Tue, Mar 20, 2012 at 5:46 AM, Deborah <falcone...@gmail.com> wrote:
Thanks, but maybe the only solution is to read the source code!!!
Careful you don't fall in...
--
unsubscribe: android-kerne...@googlegroups.com
website: http://groups.google.com/group/android-kernel
David Ahern
Mar 19, 2012, 1:32:53 PM3/19/12
to Deborah, android...@googlegroups.com
On 3/19/12 11:22 AM, Deborah wrote:
> Glenn thanks for your reply! I'm really confused. Could you explain
> how the CFS work?
> Does it divide the CPU time into epochs?
> In a single epoch, has every process a specified time quantum that is
> computed at the beginning of each epoch?
> If yes, is 'virtual runtime' set to zero in each epoch or is it an
> approximated average?
> Help please!!! :(
> Glenn thanks for your reply! I'm really confused. Could you explain
> how the CFS work?
> Does it divide the CPU time into epochs?
> In a single epoch, has every process a specified time quantum that is
> computed at the beginning of each epoch?
> If yes, is 'virtual runtime' set to zero in each epoch or is it an
> approximated average?
> Help please!!! :(
One of the better explanations of CFS:
http://lwn.net/Articles/404993/
David
Tsai Gaggery
Mar 19, 2012, 9:58:05 PM3/19/12
to android...@googlegroups.com
I think the chapter 2 of Professional Linux Kernel Architecture will
be helpful to understand the CFS. It not only describes the concept
but source code exploring.
be helpful to understand the CFS. It not only describes the concept
but source code exploring.
2012/3/20 Glenn Kasten <gka...@android.com>:
> --
> unsubscribe: android-kerne...@googlegroups.com
> website: http://groups.google.com/group/android-kernel
--
Regards,
Gaggery
Deborah
Mar 23, 2012, 11:31:46 AM3/23/12
to Android Linux Kernel Development
Thanks Gaggery!
On Mar 20, 2:58 am, Tsai Gaggery <gaggery.t...@gmail.com> wrote:
> I think the chapter 2 of Professional Linux Kernel Architecture will
> be helpful to understand the CFS. It not only describes the concept
> but source code exploring.
>
> 2012/3/20 Glenn Kasten <gkas...@android.com>:
On Mar 20, 2:58 am, Tsai Gaggery <gaggery.t...@gmail.com> wrote:
> I think the chapter 2 of Professional Linux Kernel Architecture will
> be helpful to understand the CFS. It not only describes the concept
> but source code exploring.
>
>
>
>
>
>
>
>
>
>
> > I'm sorry but generic Linux is beyond the scope of this group. I suggest
> > doing a web search for the specific topics you're interested in. However,
> > here are a few links to help you get started:
> > http://en.wikipedia.org/wiki/Completely_Fair_Scheduler
> > http://www.ibm.com/developerworks/linux/library/l-completely-fair-sch...
>
>
>
>
>
>
>
>
> > I'm sorry but generic Linux is beyond the scope of this group. I suggest
> > doing a web search for the specific topics you're interested in. However,
> > here are a few links to help you get started:
> > http://en.wikipedia.org/wiki/Completely_Fair_Scheduler
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