// SPDX-License-Identifier: GPL-2.0/* Manage affinity to optimize IPIs inside the kernel perf API. */#define _GNU_SOURCE 1#include <sched.h>#include <stdlib.h>#include <linux/bitmap.h>#include <linux/zalloc.h>#include <perf/cpumap.h>#include "perf.h"#include "cpumap.h"#include "affinity.h" static int get_cpu_set_size(void){	int sz = cpu__max_cpu().cpu + 8 - 1;	/*	 * sched_getaffinity doesn't like masks smaller than the kernel.	 * Hopefully that's big enough.	 */	if (sz < 4096)		sz = 4096;	return sz / 8;} int affinity__setup(struct affinity *a){	int cpu_set_size = get_cpu_set_size(); 	a->orig_cpus = bitmap_zalloc(cpu_set_size * 8);	if (!a->orig_cpus)		return -1;	sched_getaffinity(0, cpu_set_size, (cpu_set_t *)a->orig_cpus);	a->sched_cpus = bitmap_zalloc(cpu_set_size * 8);	if (!a->sched_cpus) {		zfree(&a->orig_cpus);		return -1;	}	bitmap_zero((unsigned long *)a->sched_cpus, cpu_set_size);	a->changed = false;	return 0;} /* * perf_event_open does an IPI internally to the target CPU. * It is more efficient to change perf's affinity to the target * CPU and then set up all events on that CPU, so we amortize * CPU communication. */void affinity__set(struct affinity *a, int cpu){	int cpu_set_size = get_cpu_set_size(); 	/*	 * Return:	 * - if cpu is -1	 * - restrict out of bound access to sched_cpus	 */	if (cpu == -1 || ((cpu >= (cpu_set_size * 8))))		return; 	a->changed = true;	__set_bit(cpu, a->sched_cpus);	/*	 * We ignore errors because affinity is just an optimization.	 * This could happen for example with isolated CPUs or cpusets.	 * In this case the IPIs inside the kernel's perf API still work.	 */	sched_setaffinity(0, cpu_set_size, (cpu_set_t *)a->sched_cpus);	__clear_bit(cpu, a->sched_cpus);} static void __affinity__cleanup(struct affinity *a){	int cpu_set_size = get_cpu_set_size(); 	if (a->changed)		sched_setaffinity(0, cpu_set_size, (cpu_set_t *)a->orig_cpus);	zfree(&a->sched_cpus);	zfree(&a->orig_cpus);} void affinity__cleanup(struct affinity *a){	if (a != NULL)		__affinity__cleanup(a);} void cpu_map__set_affinity(const struct perf_cpu_map *cpumap){	int cpu_set_size = get_cpu_set_size();	unsigned long *cpuset = bitmap_zalloc(cpu_set_size * 8);	struct perf_cpu cpu;	unsigned int idx; 	if (!cpuset)		return; 	perf_cpu_map__for_each_cpu_skip_any(cpu, idx, cpumap)		__set_bit(cpu.cpu, cpuset); 	sched_setaffinity(0, cpu_set_size, (cpu_set_t *)cpuset);	zfree(&cpuset);}