diff --git a/tools/perf/util/string.c b/tools/perf/util/string.c
index 04743d3e903922ff5d3c3308380ace0196d6a4f4..227043577e06b4800a094d8e8e7f414d46d950e4 100644
--- a/tools/perf/util/string.c
+++ b/tools/perf/util/string.c
@@ -1,5 +1,7 @@
 #include <string.h>
+#include <stdlib.h>
 #include "string.h"
+#include "util.h"
 
 static int hex(char ch)
 {
@@ -43,3 +45,85 @@ char *strxfrchar(char *s, char from, char to)
 
 	return s;
 }
+
+#define K 1024LL
+/*
+ * perf_atoll()
+ * Parse (\d+)(b|B|kb|KB|mb|MB|gb|GB|tb|TB) (e.g. "256MB")
+ * and return its numeric value
+ */
+s64 perf_atoll(const char *str)
+{
+	unsigned int i;
+	s64 length = -1, unit = 1;
+
+	if (!isdigit(str[0]))
+		goto out_err;
+
+	for (i = 1; i < strlen(str); i++) {
+		switch (str[i]) {
+		case 'B':
+		case 'b':
+			break;
+		case 'K':
+			if (str[i + 1] != 'B')
+				goto out_err;
+			else
+				goto kilo;
+		case 'k':
+			if (str[i + 1] != 'b')
+				goto out_err;
+kilo:
+			unit = K;
+			break;
+		case 'M':
+			if (str[i + 1] != 'B')
+				goto out_err;
+			else
+				goto mega;
+		case 'm':
+			if (str[i + 1] != 'b')
+				goto out_err;
+mega:
+			unit = K * K;
+			break;
+		case 'G':
+			if (str[i + 1] != 'B')
+				goto out_err;
+			else
+				goto giga;
+		case 'g':
+			if (str[i + 1] != 'b')
+				goto out_err;
+giga:
+			unit = K * K * K;
+			break;
+		case 'T':
+			if (str[i + 1] != 'B')
+				goto out_err;
+			else
+				goto tera;
+		case 't':
+			if (str[i + 1] != 'b')
+				goto out_err;
+tera:
+			unit = K * K * K * K;
+			break;
+		case '\0':	/* only specified figures */
+			unit = 1;
+			break;
+		default:
+			if (!isdigit(str[i]))
+				goto out_err;
+			break;
+		}
+	}
+
+	length = atoll(str) * unit;
+	goto out;
+
+out_err:
+	length = -1;
+out:
+	return length;
+}
diff --git a/tools/perf/util/string.h b/tools/perf/util/string.h
index 2c84bf65ba0fac020c2df05732b4b7ee0d6afabc..e50b07f80827b7d7d0cf3a35cb4fef444e033003 100644
--- a/tools/perf/util/string.h
+++ b/tools/perf/util/string.h
@@ -5,6 +5,7 @@
 
 int hex2u64(const char *ptr, u64 *val);
 char *strxfrchar(char *s, char from, char to);
+s64 perf_atoll(const char *str);
 
 #define _STR(x) #x
 #define STR(x) _STR(x)