[LITMUS^RT] question about rtspin -- Sisu

[Sisu Xi]

Hi, Björn and Jonathan:

Thanks for your reply! Now I understand...   :)

Sisu




On Wed, Apr 17, 2013 at 9:42 AM, Jonathan Herman <hermanjl at cs.unc.edu>wrote:

> The cputime() function is in liblitmus/bin/clocks.c, and calls
> clock_gettime with CLOCK_THREAD_CPUTIME_ID. This returns the amount of CPU
> time consumed by that thread only, not the current system time.
>
>
> On Wed, Apr 17, 2013 at 5:00 AM, Björn Brandenburg <bbb at mpi-sws.org>wrote:
>
>> On 17.04.2013, at 04:57, Sisu Xi <xisisu at gmail.com> wrote:
>>
>> > I am trying to understand the rtspin program and have some question
>> about it.
>> >
>> > 1) Seems it will read execution time from a file. Is this the execution
>> time for each individual job?
>>
>> Yes
>>
>> > Is there any sample file for this? How should I format the file?
>>
>> I don't have a sample file, but the format should be fairly simple. Chris
>> Kenna implemented this; he might be able to tell you more about this.
>>
>> Anyway, the file support is entirely optional, you don't have to use it
>> (I usually don't).
>>
>> >
>> > 2) The budget enforcement, if configured as precise_enforcement, will
>> force job to yield when it exceed wcet.
>> > However, if I configure it as no_enforcement, the wcet parameter won't
>> be used. cause the scheduling decision are made based on period/deadline,
>> is this correct?
>>
>> That depends on which scheduling plugin you are using. The scheduling
>> policy has nothing to do with rtspin.
>>
>> > 3) Is it possible to run multiple rtspin task at the same time? I see
>> it records time using:
>> >
>> >       while (now + last_loop < start + exec_time) {
>> >               loop_start = now;
>> >               tmp += loop_once();
>> >               now = cputime();
>> >               last_loop = now - loop_start;
>> >
>> > If multiple tasks are running, would't the time be incorrect?
>>
>> No. Why would it?
>>
>> - Björn
>>
>>
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>> litmus-dev at lists.litmus-rt.org
>> https://lists.litmus-rt.org/listinfo/litmus-dev
>>
>
>
>
> --
> Jonathan Herman
> Department of Computer Science at UNC Chapel Hill
>
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>
>


-- 
Sisu Xi, PhD Candidate

http://www.cse.wustl.edu/~xis/
Department of Computer Science and Engineering
Campus Box 1045
Washington University in St. Louis
One Brookings Drive
St. Louis, MO 63130
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