On Thu, Aug 28, 2014 at 11:00:29AM +0100, Juri Lelli wrote: > Add an appendix briefly describing tools that can be used to test SCHED_DEADLINE > (and the scheduler in general). Links to where source code of the tools is hosted > are also provided. > > Signed-off-by: Juri Lelli <juri.lelli@xxxxxxx> > Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxxxxx> > Cc: Henrik Austad <henrik@xxxxxxxxx> > Cc: Dario Faggioli <raistlin@xxxxxxxx> > Cc: Juri Lelli <juri.lelli@xxxxxxxxx> > Cc: linux-doc@xxxxxxxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx > --- > Documentation/scheduler/sched-deadline.txt | 52 ++++++++++++++++++++++++++++++ > 1 file changed, 52 insertions(+) > > diff --git a/Documentation/scheduler/sched-deadline.txt b/Documentation/scheduler/sched-deadline.txt > index 641395e..2f5b174 100644 > --- a/Documentation/scheduler/sched-deadline.txt > +++ b/Documentation/scheduler/sched-deadline.txt > @@ -15,6 +15,7 @@ CONTENTS > 5. Tasks CPU affinity > 5.1 SCHED_DEADLINE and cpusets HOWTO > 6. Future plans > + A. Test suite > > > 0. WARNING > @@ -341,3 +342,54 @@ CONTENTS > throttling patches [https://lkml.org/lkml/2010/2/23/239] but we still are in > the preliminary phases of the merge and we really seek feedback that would > help us decide on the direction it should take. > + > +Appendix A. Test suite > +====================== > + > + The SCHED_DEADLINE policy can be easily tested using two applications that > + are part of a wider Linux Scheduler validation suite. The suite is > + available as a GitHub repository: https://github.com/scheduler-tools. > + > + The first testing application is called rt-app and can be used to > + start multiple threads with specific parameters. rt-app supports > + SCHED_{OTHER,FIFO,RR,DEADLINE} scheduling policies and their related > + parameters (e.g., niceness, priority, runtime/deadline/period). rt-app > + is a valuable tool, as it can be used to synthetically recreate certain > + workloads (maybe mimicking real use-cases) and evaluate how the scheduler > + behaves under such workloads. In this way, results are easily reproducible. > + rt-app is available at: https://github.com/scheduler-tools/rt-app. > + > + Thread parameters can be specified from the command line, with something like > + this: > + > + # rt-app -t 100000:10000:d -t 150000:20000:f:10 -D5 > + > + The above creates two threads. The first one, scheduled by SCHED_DEADLINE, > + executes for 10ms every 100ms and the second one, scheduled at RT priority 10 > + with SCHED_FIFO, executes for 20ms every 150ms. The configuration runs > + for 5 seconds. I'd prefer The above creates 2 threads, T1 and T2. T1 is scheduled by SCHED_DEADLINE with a 100ms period and 10ms WCET. T2 is handled by SCHED_FIFO priority 10, 150ms period and 20ms WCET. The test will run for a total of 5 seconds. One can expect the eager reader to have at least a grasp of the terminology at this stage, using WCET should be acceptable. > + > + More interestingly, configurations can be described with a json file that > + can be passed as input to rt-app with something like this: > + > + # rt-app my_config.json > + > + The parameters that can be specified with the second method are a superset > + of the command line options. Please refer to rt-app documentation for more > + details. This can be found that this url: .... > + > + The second testing application is a modification of schedtool, called > + schedtool-dl, which can be used to setup SCHED_DEADLINE parameters for a > + certain pid/application. schedtool-dl is available at: > + https://github.com/scheduler-tools/schedtool-dl.git. > + > + The usage is straightforward: > + > + # schedtool -E -t 10000000:100000000 -e ./my_cpuhog_app > + > + With this, my_cpuhog_app is put to run inside a SCHED_DEADLINE reservation > + of 10ms every 100ms (note that parameters are expressed in microseconds). > + You can also use schedtool to create a reservation for an already running > + application, given that you know its pid: > + > + # schedtool -E -t 10000000:100000000 my_app_pid > -- > 2.0.4 Would it make sense to add an appendix B with a minimal SCHED_DEADLINE main() ? I for one like to invent my own wheels. Just my $0.02 -- Henrik -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
