Usage Instructions

Bandwidth Management

Scheduling domain wide bandwidth management for SCHED_DEADLINE is affected by the two following tunables:
/proc/sys/kernel/sched_deadline_period_us
/proc/sys/kernel/sched_deadline_runtime_us

Setup these values so that runtime/period is the amount of CPU (of each CPU of the system, actually) you want your SCHED_DEADLINE tasks to be able to explot.

Disabling Bandwidth Management

Just issue a echo -1 > /proc/sys/kernel/sched_deadline_runtime_us

API

#define SCHED_DEADLINE  6

#define SF_SIG_RORUN     2  
#define SF_SIG_DMISS       4  
#define SF_BWRECL_DL    8  
#define SF_BWRECL_RT    16  
#define SF_BWRECL_NR    32

struct sched_param_ex {  
    int sched_priority;  
    struct timespec sched_runtime;  
    struct timespec sched_deadline;  
    struct timespec sched_period  
    int sched_flags;;  
    struct timespec curr_runtime;  
    struct timespec used_runtime;  
    struct timespec curr_deadline;

};

int sched_setscheduler_ex(pid_t pid, int policy, unsigned int len, struct sched_param_ex *param);  
int_sched_setparam_ex(pid_t pid, unsigned int, struct sched_param_ex *param);  
int sched_getparam_ex(pid_t pid, unsigned int, struct sched_param_ex *param);  
int sched_wait_interval(int flags, const struct timespec *rqtp, struct timespec *rmtp);

Example Code

...
struct sched_param_ex sched_edfp;

memset(&sched_edfp, 0, sizeof(sched_edfp));

sched_edfp.sched_priority = 0;  
sched_edfp.sched_deadline = time_to_timespec(<deadline>);  
sched_edfp.sched_runtime = time_to_timespec(<wcet>);  
sched_edfp.sched_flags = 0;  
mask = 0x1 << which_cpu;

sched_setaffinity(0, sizeof(mask), &mask);  
sched_setscheduler_ex(0, SCHED_DEADLINE, sizeof(sched_edfp), &sched_edfp);

fprintf(stderr, "task %d: START\n", gettid());

clock_gettime(CLOCK_MONOTONIC, &next);  
next.tv_sec++;  
while (<!end>) {  
    clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &next, NULL);

    nrun++;  
    printf("task %d: running cycle %d\n", pid, nrun);  
    <do your job!>

    next = timespec_add(next, <period>);  
}  
...

Binary Usage

Setup 50% bandwidth available for SCHED_DEADLINE tasks:

echo 500000 > /proc/sys/kernel/sched_rt_runtime_us
echo 100000 > /proc/sys/kernel/sched_dl_period_us  
echo 50000 > /proc/sys/kernel/sched_dl_runtime_us

Run a new task as SCHED_DEADLINE or make a running task SCHED_DEADLINE:

schedtool -E -t _runtime_:_deadline_ [-a _#CPU_] [-s] [-S] -e _command_
schedtool -E -t _runtime_:_deadline_ [-a _#CPU_] [-s] [-S] _pid_

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Created by Dario Faggioli, C 2009, 2010, 2011