/** Linux specific real-time optimizations * * @author Steffen Vogel * @copyright 2017, Institute for Automation of Complex Power Systems, EONERC * @license GNU General Public License (version 3) * * VILLASnode * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see . *********************************************************************************/ #include #include #include #include #include #include #include #include int rt_init(int priority, int affinity) { info("Initialize real-time sub-system"); { #ifdef __linux__ int is_rt; /* Use FIFO scheduler with real time priority */ is_rt = rt_is_preemptible(); if (is_rt) warn("We recommend to use an PREEMPT_RT patched kernel!"); if (priority) rt_set_priority(priority); else warn("You might want to use the 'priority' setting to increase VILLASnode's process priority"); if (affinity) rt_set_affinity(affinity); else warn("You might want to use the 'affinity' setting to pin VILLASnode to dedicate CPU cores"); rt_lock_memory(); #else warn("This platform is not optimized for real-time execution"); #endif } return 0; } #ifdef __linux__ int rt_lock_memory() { int ret; #ifdef _POSIX_MEMLOCK ret = mlockall(MCL_CURRENT | MCL_FUTURE); if (ret) error("Failed to lock memory"); #endif return 0; } int rt_set_affinity(int affinity) { char isolcpus[255]; int is_isol, ret; /* Pin threads to CPUs by setting the affinity */ cpu_set_t cset_pin, cset_isol, cset_non_isol; cpuset_from_integer(affinity, &cset_pin); is_isol = kernel_get_cmdline_param("isolcpus", isolcpus, sizeof(isolcpus)); if (is_isol) { warn("You should reserve some cores for VILLASnode (see 'isolcpus')"); CPU_ZERO(&cset_isol); } else { ret = cpulist_parse(isolcpus, &cset_isol, 0); if (ret) error("Invalid isolcpus cmdline parameter: %s", isolcpus); CPU_XOR(&cset_non_isol, &cset_isol, &cset_pin); if (CPU_COUNT(&cset_non_isol) > 0) { char isol[128], pin[128]; cpulist_create(isol, sizeof(isol), &cset_isol); cpulist_create(pin, sizeof(pin), &cset_pin); warn("Affinity setting includes cores which are not isolated: affinity=%s isolcpus=%s", pin, isol); } } char list[128]; cpulist_create(list, sizeof(list), &cset_pin); ret = sched_setaffinity(0, sizeof(cpu_set_t), &cset_pin); if (ret) serror("Failed to set CPU affinity to %s", list); debug(LOG_KERNEL | 3, "Set affinity to %s", list); return 0; } int rt_set_priority(int priority) { int ret; struct sched_param param = { .sched_priority = priority }; ret = sched_setscheduler(0, SCHED_FIFO, ¶m); if (ret) serror("Failed to set real time priority"); debug(LOG_KERNEL | 3, "Task priority set to %u", priority); return 0; } int rt_is_preemptible() { return access(SYSFS_PATH "/kernel/realtime", R_OK); } #endif /* __linux__ */