| 1 | |
| 2 |
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| 3 | #define _GNU_SOURCE 1
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| 4 | #include <sched.h>
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| 5 | #include <stdlib.h>
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| 6 | #include <linux/bitmap.h>
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| 7 | #include <linux/zalloc.h>
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| 8 | #include <perf/cpumap.h>
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| 9 | #include "perf.h"
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| 10 | #include "cpumap.h"
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| 11 | #include "affinity.h"
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| 12 |
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| 13 | static int get_cpu_set_size(void)
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| 14 | {
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| 15 | int sz = cpu__max_cpu().cpu + 8 - 1;
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| 16 | |
| 17 | * sched_getaffinity doesn't like masks smaller than the kernel.
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| 18 | * Hopefully that's big enough.
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| 19 |
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| 20 | if (sz < 4096)
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| 21 | sz = 4096;
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| 22 | return sz / 8;
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| 23 | }
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| 24 |
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| 25 | int affinity__setup(struct affinity *a)
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| 26 | {
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| 27 | int cpu_set_size = get_cpu_set_size();
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| 28 |
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| 29 | a->orig_cpus = bitmap_zalloc(cpu_set_size * 8);
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| 30 | if (!a->orig_cpus)
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| 31 | return -1;
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| 32 | sched_getaffinity(0, cpu_set_size, (cpu_set_t *)a->orig_cpus);
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| 33 | a->sched_cpus = bitmap_zalloc(cpu_set_size * 8);
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| 34 | if (!a->sched_cpus) {
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| 35 | zfree(&a->orig_cpus);
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| 36 | return -1;
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| 37 | }
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| 38 | bitmap_zero((unsigned long *)a->sched_cpus, cpu_set_size);
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| 39 | a->changed = false;
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| 40 | return 0;
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| 41 | }
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| 42 |
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| 43 | |
| 44 | * perf_event_open does an IPI internally to the target CPU.
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| 45 | * It is more efficient to change perf's affinity to the target
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| 46 | * CPU and then set up all events on that CPU, so we amortize
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| 47 | * CPU communication.
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| 48 |
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| 49 | void affinity__set(struct affinity *a, int cpu)
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| 50 | {
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| 51 | int cpu_set_size = get_cpu_set_size();
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| 52 |
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| 53 | |
| 54 | * Return:
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| 55 | * - if cpu is -1
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| 56 | * - restrict out of bound access to sched_cpus
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| 57 |
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| 58 | if (cpu == -1 || ((cpu >= (cpu_set_size * 8))))
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| 59 | return;
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| 60 |
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| 61 | a->changed = true;
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| 62 | __set_bit(cpu, a->sched_cpus);
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| 63 | |
| 64 | * We ignore errors because affinity is just an optimization.
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| 65 | * This could happen for example with isolated CPUs or cpusets.
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| 66 | * In this case the IPIs inside the kernel's perf API still work.
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| 67 |
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| 68 | sched_setaffinity(0, cpu_set_size, (cpu_set_t *)a->sched_cpus);
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| 69 | __clear_bit(cpu, a->sched_cpus);
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| 70 | }
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| 71 |
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| 72 | static void __affinity__cleanup(struct affinity *a)
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| 73 | {
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| 74 | int cpu_set_size = get_cpu_set_size();
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| 75 |
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| 76 | if (a->changed)
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| 77 | sched_setaffinity(0, cpu_set_size, (cpu_set_t *)a->orig_cpus);
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| 78 | zfree(&a->sched_cpus);
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| 79 | zfree(&a->orig_cpus);
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| 80 | }
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| 81 |
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| 82 | void affinity__cleanup(struct affinity *a)
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| 83 | {
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| 84 | if (a != NULL)
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| 85 | __affinity__cleanup(a);
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| 86 | }
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| 87 |
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| 88 | void cpu_map__set_affinity(const struct perf_cpu_map *cpumap)
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| 89 | {
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| 90 | int cpu_set_size = get_cpu_set_size();
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| 91 | unsigned long *cpuset = bitmap_zalloc(cpu_set_size * 8);
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| 92 | struct perf_cpu cpu;
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| 93 | unsigned int idx;
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| 94 |
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| 95 | if (!cpuset)
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| 96 | return;
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| 97 |
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| 98 | perf_cpu_map__for_each_cpu_skip_any(cpu, idx, cpumap)
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| 99 | __set_bit(cpu.cpu, cpuset);
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| 100 |
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| 101 | sched_setaffinity(0, cpu_set_size, (cpu_set_t *)cpuset);
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| 102 | zfree(&cpuset);
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| 103 | }
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