[LITMUS^RT] Trace unit ?

[Sanjib Das]

Hi Glenn,

Thank you for the clarification. Can you please give me an idea about how
can I measure the cpu utilization for the scheduling algorithms with the
existing option in LITMUS-RT/ experiment-scripts?

Thanks in advance

Sanjib



On Thu, Jun 19, 2014 at 1:43 PM, Glenn Elliott <gelliott at cs.unc.edu> wrote:

>
> On Jun 19, 2014, at 7:09 AM, Sanjib Das <cnt.sanjib at googlemail.com> wrote:
>
> Hi,
> Thank you very much. But, For each experiment with PFAIR scrip returns 3
> couples of  CSVs and PDFs. Where PDFs are labeled as CXS_task_Avg_Avg,
> CXS_task_Min_Min, CXS_task_Min_Avg, CXS_task_Var_Avg, CXS_task_Max_Max,
> CXS_task_Max_Avg, and there is not label on the generated graph .
>
> Can you please help me in this particulate case  ?
>
> Thanks in advance
> Sanjib
>
>
> On Thu, Jun 19, 2014 at 1:05 PM, Björn Brandenburg <bbb at mpi-sws.org>
> wrote:
>
>>
>> On 19 Jun 2014, at 12:03, Sanjib Das <cnt.sanjib at googlemail.com> wrote:
>>
>> • RELEASE_LATENCY: Used to measure the difference between when a
>> timer should have fired, and when it actually did fire. In contrast to all
>> other time stamps, this overhead is directly measured in
>> nanoseconds(**********and not in processor cycles as the other
>> overheads*********).
>>
>>
>> Except RELEASE_LATENCY, are all the others measured in milliseconds ?
>>
>> Or how can I determine that .
>>
>>
>> See above. Feather-Trace reports processor cycles.
>>
>> - Björn
>>
>>
> Hi Sanjib,
>
> Digging into the mailing list archives…
> https://lists.litmus-rt.org/pipermail/litmus-dev/2014/000964.html
>
> Check out the section labeled “Overheads.”  Overheads should be in
> microseconds.
>
> Regarding the particular measurements that you mention:
>
> CXS_task_Avg_Avg: The average of average context switch overhead measured
> in each tested task set.  If you’re interested in average case overheads,
> this is probably the one that you want.
>
> CXS_task_Min_Min: The minimum context switch overhead observed across all
> run task sets.
>
> CXS_task_Min_Avg: The minimum average context switch overhead measured
> across tested task sets.
>
> CXS_task_Max_Max and CXS_task_Max_Avg: Like the corresponding Min types,
> but for maximum values.
>
> CXS_task_Var_Avg: The variance in context switch averages measured within
> each task set. (???)
>
> The experiment-scripts auto-generates these graphs, so the graphs are very
> simple and they lack labels.  Please note that the generated graphs do not
> always make sense—the scripts aren’t smart enough to understand the context
> of the data.  From the scripts’s point of view, it was given data and told
> to plot it.  If you want to perform deeper analysis or create prettier
> graphs, you’ll have to process the data from the csv files stored in the
> directory hierarchy output by the scripts.
>
> Finally, as noted above, release latency is measured by litmus in
> nanoseconds.  I think that there may be a bug in experiment-scripts.  I
> think it probably thinks it is in cycles as well.  I’ll look into this.
>
> -Glenn
>
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>
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