perf tools: Add unit_number__scnprintf function

Add unit_number__scnprintf function to display size units and use it in
-m option info message.

Before:
  $ perf record -m 10M ls
  rounding mmap pages size to 16777216 bytes (4096 pages)
  ...

After:
  $ perf record -m 10M ls
  rounding mmap pages size to 16M (4096 pages)
  ...

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1483955520-29063-2-git-send-email-jolsa@kernel.org
[ Rename it to unit_number__scnprintf for consistency ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/Build

@@ -44,6 +44,7 @@ perf-y += is_printable_array.o
 perf-y += bitmap.o
 perf-y += perf-hooks.o
 perf-y += clang.o
+perf-y += unit_number__scnprintf.o
 
 $(OUTPUT)tests/llvm-src-base.c: tests/bpf-script-example.c tests/Build
 	$(call rule_mkdir)

tools/perf/tests/builtin-test.c

@@ -246,6 +246,10 @@ static struct test generic_tests[] = {
 			.get_desc	= test__clang_subtest_get_desc,
 		}
 	},
+	{
+		.desc = "unit_number__scnprintf",
+		.func = test__unit_number__scnprint,
+	},
 	{
 		.func = NULL,
 	},

tools/perf/tests/tests.h

@@ -96,6 +96,7 @@ int test__perf_hooks(int subtest);
 int test__clang(int subtest);
 const char *test__clang_subtest_get_desc(int subtest);
 int test__clang_subtest_get_nr(void);
+int test__unit_number__scnprint(int subtest);
 
 #if defined(__arm__) || defined(__aarch64__)
 #ifdef HAVE_DWARF_UNWIND_SUPPORT

tools/perf/tests/unit_number__scnprintf.c

@@ -0,0 +1,37 @@
+#include <linux/compiler.h>
+#include <linux/types.h>
+#include "tests.h"
+#include "util.h"
+#include "debug.h"
+
+int test__unit_number__scnprint(int subtest __maybe_unused)
+{
+	struct {
+		u64		 n;
+		const char	*str;
+	} test[] = {
+		{ 1,			"1B"	},
+		{ 10*1024,		"10K"	},
+		{ 20*1024*1024,		"20M"	},
+		{ 30*1024*1024*1024ULL,	"30G"	},
+		{ 0,			"0B"	},
+		{ 0,			NULL	},
+	};
+	unsigned i = 0;
+
+	while (test[i].str) {
+		char buf[100];
+
+		unit_number__scnprintf(buf, sizeof(buf), test[i].n);
+
+		pr_debug("n %" PRIu64 ", str '%s', buf '%s'\n",
+			 test[i].n, test[i].str, buf);
+
+		if (strcmp(test[i].str, buf))
+			return TEST_FAIL;
+
+		i++;
+	}
+
+	return TEST_OK;
+}