diff options
| -rw-r--r-- | tools/perf/util/Build | 1 | ||||
| -rw-r--r-- | tools/perf/util/affinity.c | 73 | ||||
| -rw-r--r-- | tools/perf/util/affinity.h | 17 | ||||
| -rw-r--r-- | tools/perf/util/python-ext-sources | 1 |
4 files changed, 92 insertions, 0 deletions
diff --git a/tools/perf/util/Build b/tools/perf/util/Build index aab05e2c01a5..07da6c790b63 100644 --- a/tools/perf/util/Build +++ b/tools/perf/util/Build @@ -77,6 +77,7 @@ perf-y += sort.o perf-y += hist.o perf-y += util.o perf-y += cpumap.o +perf-y += affinity.o perf-y += cputopo.o perf-y += cgroup.o perf-y += target.o diff --git a/tools/perf/util/affinity.c b/tools/perf/util/affinity.c new file mode 100644 index 000000000000..a5e31f826828 --- /dev/null +++ b/tools/perf/util/affinity.c @@ -0,0 +1,73 @@ +// 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.h" +#include "cpumap.h" +#include "affinity.h" + +static int get_cpu_set_size(void) +{ + int sz = cpu__max_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_alloc(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_alloc(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(); + + if (cpu == -1) + 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); +} + +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); +} diff --git a/tools/perf/util/affinity.h b/tools/perf/util/affinity.h new file mode 100644 index 000000000000..0ad6a18ef20c --- /dev/null +++ b/tools/perf/util/affinity.h @@ -0,0 +1,17 @@ +// SPDX-License-Identifier: GPL-2.0 +#ifndef PERF_AFFINITY_H +#define PERF_AFFINITY_H 1 + +#include <stdbool.h> + +struct affinity { + unsigned long *orig_cpus; + unsigned long *sched_cpus; + bool changed; +}; + +void affinity__cleanup(struct affinity *a); +void affinity__set(struct affinity *a, int cpu); +int affinity__setup(struct affinity *a); + +#endif // PERF_AFFINITY_H diff --git a/tools/perf/util/python-ext-sources b/tools/perf/util/python-ext-sources index 9af183860fbd..e7279ea6043a 100644 --- a/tools/perf/util/python-ext-sources +++ b/tools/perf/util/python-ext-sources @@ -33,3 +33,4 @@ util/trace-event.c util/string.c util/symbol_fprintf.c util/units.c +util/affinity.c |