On Mon, Apr 3, 2017 at 8:06 AM, Ran Shalit <ranshalit@xxxxxxxxx> wrote: > On Mon, Apr 3, 2017 at 5:38 AM, Alison Chaiken <alison@xxxxxxxxxxxxxxxx> wrote: >> Ran Shalit <ranshalit@xxxxxxxxx> wrote: >>> I have found in >>> https://wiki.linuxfoundation.org/realtime/documentation/howto/applications/cyclic >>> that there is EDF scheduler option for creating a periodic RT thread. >>> Yet, I could not understand what's behind the EDF scheduler >> >> >> Have a look at "Using SCHED_DEADLINE" at >> >> http://elinux.org/ELC_Europe_2016_Presentations >> >> Also, look for papers on this topic by Juri Lelli. >> >> HTH, >> Alison > > Hi Alison, > > Thank you very much. > I reviewed the material, which is very interesting, but I am not yet > sure which timer are used internally in SCHED_DEADLINE. > Is it posix or non-posix ? > > Thanks, > Ran I am trying to understand which scheduler is better used with RT. In the wiki there is an example for SCHED_FIFO, periodic time. But in sched_deadline wiki ( https://wiki.automotivelinux.org/sched_deadline ) it is said as following: " Using SCHED_FIFO/SCHED_RR, instead, we can give that kind of guarantee only using a global period, with the constraint that “a subgroup must have a smaller or equal period to its parent”. The latency experienced by a task (i.e., the time between two consecutive executions of a task) is not deterministic and cannot be bound, since it highly depends on the number of tasks running in the system at that time. Using EDF, instead, this time is deterministic, bounded and known at any instant of time." I am not sure now. Does it mean that using more than one SCHED_FIFO periodic thread is not deterministic compared with SCHED_DEADLINE? Regards, Ran -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
