On Mon, Jun 1, 2009 at 2:32 AM, Udo A. Steinberg
<udo@hypervisor.org> wrote:
On Mon, 1 Jun 2009 01:57:46 +0800 Sean (S) wrote:
S> Function l4_rt_generic() is implemented by inline assembly, and it seems
S> to call the system call "thread_schedule".
Indeed.
S> Because these functions only appears in ARCH-x86 directory, do they
S> support on ARM architecture?
Currently these functions are available on x86 only.
S> If not, how can I implement similar behaviors of these functions?
S> Where can I find the document about the L4 system call API ? I can't
S> really understand the behavior of these functions.
The API is described in my diploma thesis, see
http://os.inf.tu-dresden.de/papers_ps/steinberg-diplom.pdf
You would have to extend the kernel ABI (e.g., which parameters are passed
in which registers) for ARM to be able to use these extensions. Note that
the real-time scheduling code in Fiasco is quite dated. No one has used or
maintained it in the last 5 years.
S> 2. When system contains three user threads, I want to control Fiasco
S> scheduler not to schedule one thread in these three threads during one
S> time interval. How can I implement it?
S> The simplest way seems to control this thread into un-running state.
S> How can I achieve this by a supervisal server?
I suggest you read the aforementioned PDF document first. It describes how
you can control thread execution with periods, deadlines and release times.
I got confused here.
I already go through your diploma thesis. This thesis describes the design issues and implementation detail of the Periodic Mode support for Fiasco. If I don't want to control thread execution with periods, deadlines and etc. , how can I implement the functionality I mentioned?
My goal is that
In the system, there are several user threads. During a time interval, some particular user threads will not be scheduled even though these threads are in ready state.
How can I implement it? Does any exist function/API support it?
I already have several directions below. I hope anyone give me some suggestions.
1. Directly change the state of these threads to non-ready by system call thread_ex_regs_sc.
But there are some problems because the thread_ex_regs_sc can be called by the thread in same address space. And I'm not sure the thread states maintained by Fiasco and whether I can change the state directly.
2. Modify the Fiasco scheduler. Before choosing the thread to schedule, the Fiasco scheduler checks a list contained un-scheduled threads IDs.
But the maintenance of this list is a problem. Maybe I need to add a new system call for this.
Thanks a lot for your reading!
Best Regards,
Sean
Cheers,
- Udo
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