[LITMUS^RT] table driven global scheduling

[Glenn Elliott]

> On Jan 28, 2020, at 3:59 AM, Björn Brandenburg <bbb at mpi-sws.org> wrote:
> 
> Dear Laurent,
> 
> On 22. Jan 2020, at 21:04, Laurent Pautet <laurent.pautet at telecom-paristech.fr> wrote:
>> 
>> i am investigating existing solutions to define a table driven scheduling with litmus. I found the table-driven scheduling tutorial.
>> It seems that it is a time partitioning scheduling but also a partitioned scheduling (tasks attached to a given core). Since it was designed in 2016, i would like to know if this has been extended to support global scheduling.
> 
> no, such a feature has not been implemented to date. 
> 
>> If not, how difficult would it be to extend the current table driven scheduling.
> 
> Conceptually not any more difficult than non-table-driven global schedulers, but it would require a bit of engineering work.  
> 
> Best,
> Björn

Herman et al. Implemented _partitioned_ table-driven scheduling in Litmus 2011.1, for their paper "RTOS Support for Mixed-Criticality Systems” (http://www.cs.unc.edu/~anderson/papers/rtas12b.pdf <http://www.cs.unc.edu/~anderson/papers/rtas12b.pdf>).  You can find it as a part of this patch: http://www.cs.unc.edu/~anderson/litmus-rt/download/RTAS12/wip-mc.patch <http://www.cs.unc.edu/~anderson/litmus-rt/download/RTAS12/wip-mc.patch> (look for code related to “cyclic executive” or “ce”).

The patch is for an old version of Litmus, and is for partitioned scheduling, but it may give you some ideas on how to approach a global table-driven scheduler (e.g., how to express the table to the scheduler—under Herman’s patch, you write a CSV file, representing the schedule table, to a file in /proc).

-Glenn
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