Scheduler.cxx

// Cosmos
#include <cosmos/error/ApiError.hxx>
#include <cosmos/error/UsageError.hxx>
#include <cosmos/private/Scheduler.hxx>
#include <cosmos/proc/Scheduler.hxx>
#include <cosmos/memory.hxx>
 
// Linux
#include <sys/syscall.h>
 
namespace cosmos {
 
constexpr int OtherSchedulerSettings::INVALID_NICE_PRIO = OtherSchedulerSettings::maxNiceValue() + 1;
 
void SchedulerSettings::apply(ProcessID pid) const {
        struct sched_attr attrs;
        this->fillStruct(attrs);
 
        // not only the data structure is not commonly defined in the C
        // headers, also the system call is not available. So we need to do it
        // ourselves.
        //
        // the POSIX interface sched_setscheduler is probably available, but
        // only supports the priority property and FIFO/RR, nothing else.
        if (::syscall(__NR_sched_setattr, pid, &attrs, 0) != 0) {
                cosmos_throw (ApiError("sched_setattr()"));
        }
}
 
int RealTimeSchedulerSettings::minPriority() const {
        auto ret = sched_get_priority_min(static_cast<int>(m_policy));
 
        if (ret == -1) {
                cosmos_throw (ApiError("sched_get_priority_min()"));
        }
 
        return ret;
}
 
int RealTimeSchedulerSettings::maxPriority() const {
        auto ret = sched_get_priority_max(static_cast<int>(m_policy));
 
        if (ret == -1) {
                cosmos_throw (ApiError("sched_get_priority_max()"));
        }
 
        return ret;
}
 
void SchedulerSettings::fillStruct(sched_attr &attr) const {
        if (m_policy == SchedulerPolicy::INVALID) {
                cosmos_throw (UsageError("Tried to fill sched_attr for invalid policy"));
        }
        zero_object(attr);
        attr.size = sizeof(attr);
        attr.sched_policy = static_cast<int>(m_policy);
}
 
void OtherSchedulerSettings::fillStruct(sched_attr &attr) const {
        SchedulerSettings::fillStruct(attr);
        attr.sched_nice = m_nice_prio;
}
 
void RealTimeSchedulerSettings::fillStruct(sched_attr &attr) const {
        SchedulerSettings::fillStruct(attr);
        attr.sched_priority = m_priority;
}
 
} // end ns