Cleanup: ust-tracepoint-event.h: extract `__num_fields` in a variable

[lttng-ust.git] / libringbuffer / getcpu.h

diff --git a/libringbuffer/getcpu.h b/libringbuffer/getcpu.h
index f5f2f67571947b6c89d693ba8b9e28777f63cd89..7b009dc6cf38efefd67aece71a8308a66a351efb 100644 (file)
--- a/libringbuffer/getcpu.h
+++ b/libringbuffer/getcpu.h
@@ -19,11 +19,16 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#define _GNU_SOURCE
 #include <urcu/compiler.h>
-#include <sched.h>
+#include <urcu/system.h>
+#include <urcu/arch.h>
+#include <config.h>
+
+void lttng_ust_getcpu_init(void);
+
+extern int (*lttng_get_cpu)(void);
 
-#ifdef UST_VALGRIND
+#ifdef LTTNG_UST_DEBUG_VALGRIND
 
 /*
  * Fallback on cpu 0 if liblttng-ust is build with Valgrind support.
@@ -31,18 +36,42 @@
  * migration, so it is only statistically accurate.
  */
 static inline
-int lttng_ust_get_cpu(void)
+int lttng_ust_get_cpu_internal(void)
 {
        return 0;
 }
 
 #else
 
+/*
+ * sched_getcpu.
+ */
+#ifdef __linux__
+
+#if !HAVE_SCHED_GETCPU
+#include <sys/syscall.h>
+#define __getcpu(cpu, node, cache)     syscall(__NR_getcpu, cpu, node, cache)
 /*
  * If getcpu is not implemented in the kernel, use cpu 0 as fallback.
  */
 static inline
-int lttng_ust_get_cpu(void)
+int lttng_ust_get_cpu_internal(void)
+{
+       int cpu, ret;
+
+       ret = __getcpu(&cpu, NULL, NULL);
+       if (caa_unlikely(ret < 0))
+               return 0;
+       return cpu;
+}
+#else /* HAVE_SCHED_GETCPU */
+#include <sched.h>
+
+/*
+ * If getcpu is not implemented in the kernel, use cpu 0 as fallback.
+ */
+static inline
+int lttng_ust_get_cpu_internal(void)
 {
        int cpu;
 
@@ -51,7 +80,36 @@ int lttng_ust_get_cpu(void)
                return 0;
        return cpu;
 }
+#endif /* HAVE_SCHED_GETCPU */
+
+#elif (defined(__FreeBSD__) || defined(__CYGWIN__))
+
+/*
+ * FreeBSD and Cygwin do not allow query of CPU ID. Always use CPU
+ * number 0, with the assocated performance degradation on SMP.
+ */
+static inline
+int lttng_ust_get_cpu_internal(void)
+{
+       return 0;
+}
+
+#else
+#error "Please add support for your OS into liblttng-ust/compat.h."
+#endif
 
 #endif
 
+static inline
+int lttng_ust_get_cpu(void)
+{
+       int (*getcpu)(void) = CMM_LOAD_SHARED(lttng_get_cpu);
+
+       if (caa_likely(!getcpu)) {
+               return lttng_ust_get_cpu_internal();
+       } else {
+               return getcpu();
+       }
+}
+
 #endif /* _LTTNG_GETCPU_H */