[LITMUS^RT] feather-Trace Results

[Andrea Bastoni]

Hi,

On 01/31/17 13:34, lambros bersentes wrote:
> Hi there,
> 
> 
> My question may sound a bit silly so sorry in advance. :)
> 
> 
> I read the very first paper concerning the Litmus Rt framework (A Testbed for
> Empirically Comparing Real-Time Multiprocessor Schedulers) and i tried to
> reproduce the results on page 7 concerning the context switching costs and
> scheduler costs.
> 
> 
> I used the feather-trace tool in order to measure the results on 3 task sets
> consisting of 10-20-50 same tasks. I am reading the stats.csv file which i get
> and to be accurate just the CXS and SCHED. I am getting all the results in
> cycles. My question is in order to be able to compare them with another tool
> (HSF) which also gives statistics,however measured in seconds, is there any
> option to calculate all the statistics in seconds instead of cycles or how can i
> output the current frequency of my CPU on which the tests were done.
> The
> frequency of my CPU is not apparently stable as it changes depending on the task
> load.

When you run experiments, make sure that either you don't use any CPU governors
(i.e., compile it out of your kernel), or that the governor doesn't allow any
frequency scaling.

See linux/Documentation/cpu-freq/governors.txt

-- 
Thanks,
Andrea