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Add fix to thread scheduling API #415

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merged 4 commits into from
Apr 28, 2024
Merged

Add fix to thread scheduling API #415

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9f0e352
sched: When requesting a RT policy, we must initialize the priority
erlingrj Apr 26, 2024
9ccfa42
Fix some typos
erlingrj Apr 26, 2024
a7ed4aa
Another typo
erlingrj Apr 26, 2024
68a7b8b
Fix the linear mapping function
erlingrj Apr 26, 2024
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31 changes: 19 additions & 12 deletions low_level_platform/impl/src/lf_linux_support.c
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Original file line number Diff line number Diff line change
Expand Up @@ -60,16 +60,17 @@ int lf_thread_set_cpu(lf_thread_t thread, int cpu_number) {
}

int lf_thread_set_priority(lf_thread_t thread, int priority) {
int posix_policy, min_pri, max_pri, final_priority;
int posix_policy, min_pri, max_pri, final_priority, res;
struct sched_param schedparam;

if (priority > LF_SCHED_MAX_PRIORITY || priority < LF_SCHED_MIN_PRIORITY) {
return -1;
}

// Get the current scheduling policy
if (pthread_getschedparam(thread, &posix_policy, &schedparam) != 0) {
return -1;
res = pthread_getschedparam(thread, &posix_policy, &schedparam);
if (res != 0) {
return res;
}

min_pri = sched_get_priority_min(posix_policy);
Expand All @@ -87,39 +88,45 @@ int lf_thread_set_priority(lf_thread_t thread, int priority) {
}

int lf_thread_set_scheduling_policy(lf_thread_t thread, lf_scheduling_policy_t* policy) {
int posix_policy;
int posix_policy, res;
struct sched_param schedparam;

// Get the current scheduling policy
if (pthread_getschedparam(thread, &posix_policy, &schedparam) != 0) {
return -1;
res = pthread_getschedparam(thread, &posix_policy, &schedparam);
if (res != 0) {
return res;
}

// Update the policy
// Update the policy, and initially set the priority to max.
// The priority value is later updated. Initializing it
// is just to avoid code duplication.
switch (policy->policy) {
case LF_SCHED_FAIR:
posix_policy = SCHED_OTHER;
break;
case LF_SCHED_TIMESLICE:
posix_policy = SCHED_RR;
schedparam.sched_priority = sched_get_priority_max(SCHED_RR);
break;
case LF_SCHED_PRIORITY:
posix_policy = SCHED_FIFO;
schedparam.sched_priority = sched_get_priority_max(SCHED_FIFO);
break;
default:
return -1;
break;
}

// Write it back
if (pthread_setschedparam(thread, posix_policy, &schedparam) != 0) {
return -3;
res = pthread_setschedparam(thread, posix_policy, &schedparam);
if (res != 0) {
return res;
}

// Set the priority
if (lf_thread_set_priority(thread, policy->priority) != 0) {
return -1;
}
res = lf_thread_set_priority(thread, policy->priority);
if (res != 0)
return res;

return 0;
}
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7 changes: 4 additions & 3 deletions low_level_platform/impl/src/lf_platform_util.c
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Original file line number Diff line number Diff line change
Expand Up @@ -7,9 +7,10 @@ int map_priorities(int priority, int dest_min, int dest_max) {
return -1;
}

// Perform the linear mapping
return dest_min +
((dest_max - dest_min) / (LF_SCHED_MAX_PRIORITY - LF_SCHED_MIN_PRIORITY)) * (priority - LF_SCHED_MIN_PRIORITY);
// Perform the linear mapping. Since we are working with integers, it is
// important to multiply before we divide
return dest_min + (((priority - LF_SCHED_MIN_PRIORITY) * (dest_max - dest_min)) /
(LF_SCHED_MAX_PRIORITY - LF_SCHED_MIN_PRIORITY));
}

#ifndef PLATFORM_ZEPHYR // on Zephyr, this is handled separately
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