JanStaschulat edited a comment on issue #2935: URL: https://github.com/apache/incubator-nuttx/issues/2935#issuecomment-788032529
Thanks for your quick feedback. I ran a couple of experiments with this [test program](https://github.com/micro-ROS/nuttx_apps/blob/feature/foxy_rbs_one_sporadic_thread/examples/uros_rbs/main_rbs.c) Some links to the source code: - creation of sporadic thread 1 [here](https://github.com/micro-ROS/nuttx_apps/blob/a60f50b74ccc134b11ad4eecae2b93d78a031d46/examples/uros_rbs/main_rbs.c#L322) - creation of sporadic thread 2 [here](https://github.com/micro-ROS/nuttx_apps/blob/a60f50b74ccc134b11ad4eecae2b93d78a031d46/examples/uros_rbs/main_rbs.c#L355) - creating of fifo thread [here](https://github.com/micro-ROS/nuttx_apps/blob/a60f50b74ccc134b11ad4eecae2b93d78a031d46/examples/uros_rbs/main_rbs.c#L379) - thread 1 worker function [here](https://github.com/micro-ROS/nuttx_apps/blob/a60f50b74ccc134b11ad4eecae2b93d78a031d46/examples/uros_rbs/main_rbs.c#L149) - main thread waits for 10 seconds [here](https://github.com/micro-ROS/nuttx_apps/blob/a60f50b74ccc134b11ad4eecae2b93d78a031d46/examples/uros_rbs/main_rbs.c#L417) The results show, that NuttX does not schedule two sporadic threads according to the specified budgets: - I varied the budget of tread one and kept the budget of the sporadic threat two at 30% - I varied the budget of tread two and kept the budget of the sporadic threat one at 30% - I ran the experiment with same priorities for sporadic thread one and sporadic thread two ``` Experimental Results: Setup: config: thread 1: - SCHED_SPORADIC, - prio high 180, prio low 20, - budget 10ms, period 100ms - max replenishments = 100 thread 2: - FIFO-thread, - prio: 120 thread 3: - SCHED_SPORADIC, - prio high 179, prio low 19, - budget 30ms, period 100ms - max replenishments = 100 - Hardware: - Olimex board (STM32), - NuttX OS Experiment: - callback function in each thread has a busy_loop of 1ms and increments a counter - experiment runs for 10 seconds - at the end the counter values of all threads are reported, e.g. the number of milliseconds the thread could execute in interval of 10 seconds (total 10000 milliseconds) Exp 1: (one sporadic thread and FIFO thread) configuration with - thread 1: sporadic thread with budget = x ms and period=100ms - thread 2: low-prio FIFO thread config result result sporadic 1 sporadic 1 fifo budget(ms) (ms) (ms) --------------------------------- 0 96 9815 10 1074 8837 20 2043 7868 30 3014 6896 40 3985 5925 50 4956 4953 60 5920 3990 70 6899 3010 80 7870 2039 90 8804 1105 100 9910 0 Exp 2 (two sporadic threads and FIFO thread) Keep sporadic thread 2 with 30/100ms budget/period, vary budget of thread 1 from 0 - 100ms configuration with - thread 1: sporadic thread with budget = x ms and period=100ms, prio see above - thread 3: sporadic thread with budget = 30 ms and period=100ms, prio see above - thread 2: low-prio FIFO thread, prio see above config result result result sporadic 1 sporadic 1 sporadic 2 fifo budget(ms) (ms) (ms) (ms) ------------------------------------------ 0 145 981 8784 10 1073 971 7864 20 2044 10 7854 30 3013 0 6895 40 9909 0 0 50 9909 0 0 60 9909 0 0 70 9909 0 0 80 9908 0 0 90 9908 0 0 100 9909 0 0 Exp 3 (two sporadic threads and FIFO thread) Keep sporadic thread 1 with 30/100ms budget, vary budget of thread 2 from 0 - 100ms configuration with - thread 1: sporadic thread with budget = 30 ms and period=100ms, prio see above - thread 3: sporadic thread with budget = x ms and period=100ms, prio see above - thread 2: low-prio FIFO thread, prio see above config result result result sporadic 2 sporadic 1 sporadic 2 fifo budget(ms) (ms) (ms) (ms) ---------------------------------------- 0 5246 4661 0 10 7091 2816 0 20 9132 776 0 30 3015 0 6892 40 3016 9 6883 50 3015 49 6844 60 3016 2311 4581 70 3065 2484 4359 80 3015 48 6845 90 3015 91 6802 100 3053 4726 2128 Exp 4 (two sporadic threads and FIFO thread) Same as Experiment 1, but both sporadic threads with the same priority settings - sporadic 1: high prio 180, low prio 20 - sporadic 2: high prio 180, low prio 20 - fifo : prio 120 config result result result sporadic 1 sporadic 1 sporadic 2 fifo budget(ms) (ms) (ms) (ms) ------------------------------------------ 0 144 981 8784 10 1073 971 7864 20 2044 10 7854 30 3015 0 6892 40 39 3044 6825 50 4957 4950 0 60 4427 1559 3923 70 6880 3028 0 80 7840 2066 0 90 8802 1105 0 100 9861 47 0 Example raw output: Sporadic thread 1: prio high: 180, low: 20, budget: 10000000 pthread_create: budget 0 s 10000000 ns ticks: 10 , period 0 s 100000000 ns ticks 100 thread id 8 sporadic thread 2: at prio high 179 low: 19, budget: 30000000 pthread_create: budget 0 s 30000000 ns ticks: 30 , period 0 s 100000000 ns ticks 100 thread id 9 FIFO thread: prio 120 thread id 10 Result: sporadic 1 1074 ms sporadic 2 19 FIFO 8816 ms ``` Conclustions: - NuttX works well with one sporadic thread and one fifo thread - NuttX does not work for - two sporadic threads and a (backround) fifo thread (varied budget of thread 1 and thread 2) - two sporadic threads with the same or with different priority settings - I disagree with the necessity of a third higher prio thread: with sporadic scheduling: This is the work-conserving nature of sched_sporadic: If the processor is idle then a sporadic thread will continue to execute with its low priority, even though its budget is depleted. - ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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