| 1 | /* |
| 2 | * SPDX-License-Identifier: MIT |
| 3 | * |
| 4 | * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 5 | */ |
| 6 | |
| 7 | #ifndef _UST_COMMON_SMP_H |
| 8 | #define _UST_COMMON_SMP_H |
| 9 | |
| 10 | #define LTTNG_UST_CPUMASK_SIZE 4096 |
| 11 | |
| 12 | /* |
| 13 | * Get a CPU mask string from sysfs. |
| 14 | * |
| 15 | * buf: the buffer where the mask will be read. |
| 16 | * max_bytes: the maximum number of bytes to write in the buffer. |
| 17 | * path: file path to read the mask from. |
| 18 | * |
| 19 | * Returns the number of bytes read or -1 on error. |
| 20 | */ |
| 21 | int get_cpu_mask_from_sysfs(char *buf, size_t max_bytes, const char *path) |
| 22 | __attribute__((visibility("hidden"))); |
| 23 | |
| 24 | /* |
| 25 | * Get the CPU possible mask string from sysfs. |
| 26 | * |
| 27 | * buf: the buffer where the mask will be read. |
| 28 | * max_bytes: the maximum number of bytes to write in the buffer. |
| 29 | * |
| 30 | * Returns the number of bytes read or -1 on error. |
| 31 | */ |
| 32 | int get_possible_cpu_mask_from_sysfs(char *buf, size_t max_bytes) |
| 33 | __attribute__((visibility("hidden"))); |
| 34 | |
| 35 | /* |
| 36 | * Get the highest CPU id from sysfs. |
| 37 | * |
| 38 | * Iterate on all the folders in "/sys/devices/system/cpu" that start with |
| 39 | * "cpu" followed by an integer, keep the highest CPU id encountered during |
| 40 | * this iteration and add 1 to get a number of CPUs. |
| 41 | * |
| 42 | * Returns the highest CPU id, or -1 on error. |
| 43 | */ |
| 44 | int get_max_cpuid_from_sysfs(void) |
| 45 | __attribute__((visibility("hidden"))); |
| 46 | |
| 47 | int _get_max_cpuid_from_sysfs(const char *path) |
| 48 | __attribute__((visibility("hidden"))); |
| 49 | |
| 50 | /* |
| 51 | * Get the number of possible CPUs in the system from either |
| 52 | * sysconf(_SC_NPROCESSORS_CONF) or some other mechanism depending on the libc. |
| 53 | * |
| 54 | * Returns the number of possible CPUs in the system or 0 on error. |
| 55 | */ |
| 56 | int get_num_possible_cpus_fallback(void) |
| 57 | __attribute__((visibility("hidden"))); |
| 58 | |
| 59 | /* |
| 60 | * Get the highest CPU id from a CPU mask. |
| 61 | * |
| 62 | * pmask: the mask to parse. |
| 63 | * len: the len of the mask excluding '\0'. |
| 64 | * |
| 65 | * Returns the highest CPU id from the mask or -1 on error. |
| 66 | */ |
| 67 | int get_max_cpuid_from_mask(const char *pmask, size_t len) |
| 68 | __attribute__((visibility("hidden"))); |
| 69 | |
| 70 | /* |
| 71 | * Returns the length of an array that could contain a per-CPU element for each |
| 72 | * possible CPU id for the lifetime of the process. |
| 73 | * |
| 74 | * We currently assume CPU ids are contiguous up the maximum CPU id. |
| 75 | * |
| 76 | * If the cache is not yet initialized, get the value from |
| 77 | * "/sys/devices/system/cpu/possible" or fallback to sysconf and cache it. |
| 78 | * |
| 79 | * If all methods fail, don't populate the cache and return 0. |
| 80 | */ |
| 81 | int get_possible_cpus_array_len(void) |
| 82 | __attribute__((visibility("hidden"))); |
| 83 | |
| 84 | #define for_each_possible_cpu(cpu) \ |
| 85 | for ((cpu) = 0; (cpu) < get_possible_cpus_array_len(); (cpu)++) |
| 86 | |
| 87 | #endif /* _UST_COMMON_SMP_H */ |