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a3a82efbf6
Try to gain SCHED_RR (round-robin) realtime scheduling privileges before starting the server. This requires CAP_SYS_NICE on Linux systems. We additionally register a pthread_atfork callback which resets the scheduling class back to SCHED_OTHER (the Linux system default). Due to CAP_SYS_NICE, setting RLIMIT_RTPRIO has no effect on the process as documented within man 7 sched (from Linux): Privileged (CAP_SYS_NICE) threads ignore the RLIMIT_RTPRIO limit; as with older kernels, they can make arbitrary changes to scheduling policy and priority. See getrlimit(2) for further information on RLIMIT_RTPRIO Note that this requires the sway distribution packagers to set the CAP_SYS_NICE capability on the sway binary. Supersedes #6992
40 lines
932 B
C
40 lines
932 B
C
#include <sys/resource.h>
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#include <sched.h>
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#include <unistd.h>
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#include <pthread.h>
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#include "sway/server.h"
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#include "log.h"
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static void child_fork_callback(void) {
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struct sched_param param;
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param.sched_priority = 0;
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int ret = pthread_setschedparam(pthread_self(), SCHED_OTHER, ¶m);
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if (ret != 0) {
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sway_log(SWAY_ERROR, "Failed to reset scheduler policy on fork");
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}
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}
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void set_rr_scheduling(void) {
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int prio = sched_get_priority_min(SCHED_RR);
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int old_policy;
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int ret;
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struct sched_param param;
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ret = pthread_getschedparam(pthread_self(), &old_policy, ¶m);
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if (ret != 0) {
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sway_log(SWAY_DEBUG, "Failed to get old scheduling priority");
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return;
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}
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param.sched_priority = prio;
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ret = pthread_setschedparam(pthread_self(), SCHED_RR, ¶m);
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if (ret != 0) {
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sway_log(SWAY_INFO, "Failed to set scheduling priority to %d", prio);
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return;
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}
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pthread_atfork(NULL, NULL, child_fork_callback);
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}
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