1 files changed, 52 insertions, 0 deletions
diff --git a/tools/perf/util/smt.c b/tools/perf/util/smt.c
new file mode 100644
index 000000000..34f1b1b11
--- /dev/null
+++ b/tools/perf/util/smt.c
@@ -0,0 +1,52 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <linux/bitops.h>
+#include "api/fs/fs.h"
+#include "smt.h"
+
+int smt_on(void)
+{
+	static bool cached;
+	static int cached_result;
+	int cpu;
+	int ncpu;
+
+	if (cached)
+		return cached_result;
+
+	if (sysfs__read_int("devices/system/cpu/smt/active", &cached_result) >= 0)
+		goto done;
+
+	ncpu = sysconf(_SC_NPROCESSORS_CONF);
+	for (cpu = 0; cpu < ncpu; cpu++) {
+		unsigned long long siblings;
+		char *str;
+		size_t strlen;
+		char fn[256];
+
+		snprintf(fn, sizeof fn,
+			"devices/system/cpu/cpu%d/topology/core_cpus", cpu);
+		if (sysfs__read_str(fn, &str, &strlen) < 0) {
+			snprintf(fn, sizeof fn,
+				"devices/system/cpu/cpu%d/topology/thread_siblings",
+				cpu);
+			if (sysfs__read_str(fn, &str, &strlen) < 0)
+				continue;
+		}
+		/* Entry is hex, but does not have 0x, so need custom parser */
+		siblings = strtoull(str, NULL, 16);
+		free(str);
+		if (hweight64(siblings) > 1) {
+			cached_result = 1;
+			cached = true;
+			break;
+		}
+	}
+	if (!cached) {
+		cached_result = 0;
+done:
+		cached = true;
+	}
+	return cached_result;
+}