v4.19.13 snapshot.
diff --git a/tools/perf/util/smt.c b/tools/perf/util/smt.c
new file mode 100644
index 0000000..453f6f6
--- /dev/null
+++ b/tools/perf/util/smt.c
@@ -0,0 +1,44 @@
+#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;
+
+ 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/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;
+ cached = true;
+ }
+ return cached_result;
+}