X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=src%2Fcommon%2Fsmp.h;h=0a8433f3dc08222e287e79cab4ed7ce7ec3eed2a;hb=82235210bea4ed2e09bf485a49baf2db6287810f;hp=563fe623591d46821664dcd6cb3750d421f85188;hpb=74cc1f594e05b5a3524529f018d85efaad53f9a3;p=lttng-ust.git

diff --git a/src/common/smp.h b/src/common/smp.h
index 563fe623..0a8433f3 100644
--- a/src/common/smp.h
+++ b/src/common/smp.h
@@ -7,15 +7,81 @@
 #ifndef _UST_COMMON_SMP_H
 #define _UST_COMMON_SMP_H
 
+#define LTTNG_UST_CPUMASK_SIZE 4096
+
+/*
+ * Get a CPU mask string from sysfs.
+ *
+ * buf: the buffer where the mask will be read.
+ * max_bytes: the maximum number of bytes to write in the buffer.
+ * path: file path to read the mask from.
+ *
+ * Returns the number of bytes read or -1 on error.
+ */
+int get_cpu_mask_from_sysfs(char *buf, size_t max_bytes, const char *path)
+	__attribute__((visibility("hidden")));
+
+/*
+ * Get the CPU possible mask string from sysfs.
+ *
+ * buf: the buffer where the mask will be read.
+ * max_bytes: the maximum number of bytes to write in the buffer.
+ *
+ * Returns the number of bytes read or -1 on error.
+ */
+int get_possible_cpu_mask_from_sysfs(char *buf, size_t max_bytes)
+	__attribute__((visibility("hidden")));
+
+/*
+ * Get the highest CPU id from sysfs.
+ *
+ * Iterate on all the folders in "/sys/devices/system/cpu" that start with
+ * "cpu" followed by an integer, keep the highest CPU id encountered during
+ * this iteration and add 1 to get a number of CPUs.
+ *
+ * Returns the highest CPU id, or -1 on error.
+ */
+int get_max_cpuid_from_sysfs(void)
+	__attribute__((visibility("hidden")));
+
+int _get_max_cpuid_from_sysfs(const char *path)
+	__attribute__((visibility("hidden")));
+
+/*
+ * Get the number of possible CPUs in the system from either
+ * sysconf(_SC_NPROCESSORS_CONF) or some other mechanism depending on the libc.
+ *
+ * Returns the number of possible CPUs in the system or 0 on error.
+ */
+int get_num_possible_cpus_fallback(void)
+	__attribute__((visibility("hidden")));
+
 /*
- * Returns the total number of CPUs in the system. If the cache is not yet
- * initialized, get the value from the system through sysconf and cache it.
+ * Get the highest CPU id from a CPU mask.
+ *
+ * pmask: the mask to parse.
+ * len: the len of the mask excluding '\0'.
+ *
+ * Returns the highest CPU id from the mask or -1 on error.
+ */
+int get_max_cpuid_from_mask(const char *pmask, size_t len)
+	__attribute__((visibility("hidden")));
+
+/*
+ * Returns the length of an array that could contain a per-CPU element for each
+ * possible CPU id for the lifetime of the process.
+ *
+ * We currently assume CPU ids are contiguous up the maximum CPU id.
+ *
+ * If the cache is not yet initialized, get the value from
+ * "/sys/devices/system/cpu/possible" or fallback to sysconf and cache it.
  *
- * If the sysconf call fails, don't populate the cache and return 0.
+ * If all methods fail, don't populate the cache and return 0.
  */
-int num_possible_cpus(void);
+int get_possible_cpus_array_len(void)
+	__attribute__((visibility("hidden")));
 
 #define for_each_possible_cpu(cpu)		\
-	for ((cpu) = 0; (cpu) < num_possible_cpus(); (cpu)++)
+	for ((cpu) = 0; (cpu) < get_possible_cpus_array_len(); (cpu)++)
 
 #endif /* _UST_COMMON_SMP_H */