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| -rw-r--r-- | Documentation/scheduler/sched-deadline.txt | 52 |
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diff --git a/Documentation/scheduler/sched-deadline.txt b/Documentation/scheduler/sched-deadline.txt index 0ce5e2c9ab7c..b4aad31cf3be 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 @@ -345,3 +346,54 @@ 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 2 threads. The first one, scheduled by SCHED_DEADLINE, + executes for 10ms every 100ms. The second one, scheduled at SCHED_FIFO + priority 10, executes for 20ms every 150ms. The test will run for a total + of 5 seconds. + + 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 (<rt-app-sources>/doc/*.json). + + 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 |