[LITMUS^RT] rtspin running 100% or 90% of wcet? -- Sisu

[Jonathan Herman]

Disclaimer: the <2% is a guess, not a fact. I haven't measured the exact
difference between rtspins WCET and actual execution time with a 1.0 scale.


On Wed, Apr 17, 2013 at 6:16 PM, Jonathan Herman <hermanjl at cs.unc.edu>wrote:

> If you use budget enforcement, then yes, that is a reasonable number for
> preventing WCET overruns. .98 would probably work as well. Without budget
> enforcement, I wouldn't worry about specifying a scale. Leave it at 1.0 as
> your jobs will be off by <2%.
>
>
> On Wed, Apr 17, 2013 at 5:07 PM, Sisu Xi <xisisu at gmail.com> wrote:
>
>> HI, Glenn:
>>
>> Thanks for your reply.
>>
>> If the scale is set to 1.0, which means all the overhead is *not* counted.
>>
>> Usually what's the value for the scale parameter as a reasonable setting
>> on a standard intel 64bit platform? 0.95?
>>
>> Thanks.
>>
>> Sisu
>>
>>
>> On Wed, Apr 17, 2013 at 4:04 PM, Glenn Elliott <gelliott at cs.unc.edu>wrote:
>>
>>> Yes.  The 90% thing is out of date.  Use the scale parameter.
>>>
>>> -Glenn
>>>
>>> On Apr 17, 2013, at 4:58 PM, Sisu Xi <xisisu at gmail.com> wrote:
>>>
>>> Hi, all:
>>>
>>> I was reading the mailing list and found this discussion:
>>>
>>> https://lists.litmus-rt.org/pipermail/litmus-dev/2012/000095.html
>>>
>>> It says rtspin cuts the wcet to 90% of its actual specified wcet.
>>>
>>> Is it the same for the current release?
>>>
>>> I check the code and cannot find where does this 90% coming from.
>>>
>>> It has the "scale" variable, but is set to 1.0
>>>
>>> Thanks very much!
>>>
>>> Sisu
>>>
>>>
>>> --
>>> 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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>>> https://lists.litmus-rt.org/listinfo/litmus-dev
>>>
>>>
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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
>>
>> _______________________________________________
>> litmus-dev mailing list
>> 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
>



-- 
Jonathan Herman
Department of Computer Science at UNC Chapel Hill
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