[PATCH v2 1/3] test_bitmap: extract benchmark module

[Tamir Duberstein <tamird@kernel.org>]

From: Tamir Duberstein <tamird@gmail.com>

Add CONFIG_BITMAP_BENCHMARK to build benchmarks separately from unit
tests. The new module is marked authored by the author of commit
991e5583647d ("lib/test_bitmap: add tests for bitmap_{read,write}()")
which added these benchmarks.

Extract duplicated code between `test_bitmap_{read,write}_perf`.

Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
---
 MAINTAINERS            |  1 +
 lib/Kconfig.debug      |  8 +++++
 lib/Makefile           |  1 +
 lib/bitmap_benchmark.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/test_bitmap.c      | 50 ----------------------------
 5 files changed, 99 insertions(+), 50 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index 5b11839cba9d..4ddaef15b408 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4426,6 +4426,7 @@ F:	include/uapi/linux/bits.h
 F:	include/vdso/bits.h
 F:	lib/bitmap-str.c
 F:	lib/bitmap.c
+F:	lib/bitmap_benchmark.c
 F:	lib/cpumask.c
 F:	lib/find_bit.c
 F:	lib/find_bit_benchmark.c
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index ba36939fda79..60434b31a940 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2492,6 +2492,14 @@ config FFS_KUNIT_TEST
 config TEST_KSTRTOX
 	tristate "Test kstrto*() family of functions at runtime"
 
+config BITMAP_BENCHMARK
+	tristate "Benchmark bitmap_*() family of functions"
+	help
+	  This builds the "bitmap_benchmark_test" module that measure bitmap_*()
+	  family of functions performance.
+
+	  If unsure, say N.
+
 config TEST_BITMAP
 	tristate "Test bitmap_*() family of functions at runtime"
 	help
diff --git a/lib/Makefile b/lib/Makefile
index aaf677cf4527..892cb3152b65 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -61,6 +61,7 @@ obj-y += string_helpers.o
 obj-y += hexdump.o
 obj-$(CONFIG_TEST_HEXDUMP) += test_hexdump.o
 obj-y += kstrtox.o
+obj-$(CONFIG_BITMAP_BENCHMARK) += bitmap_benchmark.o
 obj-$(CONFIG_FIND_BIT_BENCHMARK) += find_bit_benchmark.o
 obj-$(CONFIG_FIND_BIT_BENCHMARK_RUST) += find_bit_benchmark_rust.o
 obj-$(CONFIG_TEST_BPF) += test_bpf.o
diff --git a/lib/bitmap_benchmark.c b/lib/bitmap_benchmark.c
new file mode 100644
index 000000000000..47f4cea4e831
--- /dev/null
+++ b/lib/bitmap_benchmark.c
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Benchmarks for bitmap API.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/bitmap.h>
+#include <linux/init.h>
+#include <linux/ktime.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+
+/*
+ * Test bitmap should be big enough to include the cases when start is not in
+ * the first word, and start+nbits lands in the following word.
+ */
+#define TEST_BIT_LEN (1000)
+
+typedef void (*bitmap_bench_fn)(unsigned long *bitmap, unsigned long i, unsigned long nbits);
+
+static void __init bench_bitmap(bitmap_bench_fn bench_fn, const char *name)
+{
+	DECLARE_BITMAP(bitmap, TEST_BIT_LEN);
+	unsigned int cnt, nbits, i;
+	ktime_t time;
+
+	bitmap_fill(bitmap, TEST_BIT_LEN);
+	time = ktime_get();
+	for (cnt = 0; cnt < 5; cnt++) {
+		for (nbits = 1; nbits <= BITS_PER_LONG; nbits++) {
+			for (i = 0; i < TEST_BIT_LEN; i++) {
+				if (i + nbits > TEST_BIT_LEN)
+					break;
+				bench_fn(bitmap, i, nbits);
+			}
+		}
+	}
+	time = ktime_get() - time;
+	pr_info("Time spent in %s:\t%llu\n", name, time);
+}
+
+#undef TEST_BIT_LEN
+
+static inline void bitmap_read_bench(unsigned long *bitmap, unsigned long i, unsigned long nbits)
+{
+	unsigned long val;
+	/*
+	 * Prevent the compiler from optimizing away the
+	 * bitmap_read() by using its value.
+	 */
+	WRITE_ONCE(val, bitmap_read(bitmap, i, nbits));
+}
+
+static void __init test_bitmap_read_perf(void)
+{
+	bench_bitmap(bitmap_read_bench, __func__);
+}
+
+static inline void bitmap_write_bench(unsigned long *bitmap, unsigned long i, unsigned long nbits)
+{
+	unsigned long val = 0xfeedface;
+
+	bitmap_write(bitmap, val, i, nbits);
+}
+
+static void __init test_bitmap_write_perf(void)
+{
+	bench_bitmap(bitmap_write_bench, __func__);
+}
+
+static int __init bitmap_benchmark_init(void)
+{
+	test_bitmap_read_perf();
+	test_bitmap_write_perf();
+
+	return 0;
+}
+module_init(bitmap_benchmark_init);
+
+static void __exit bitmap_benchmark_exit(void)
+{
+	pr_info("Unloaded\n");
+}
+module_exit(bitmap_benchmark_exit);
+
+MODULE_AUTHOR("Alexander Potapenko <glider@google.com>");
+MODULE_DESCRIPTION("Benchmarks for bitmap API");
+MODULE_LICENSE("GPL");
diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
index c83829ef557f..f728b6485c88 100644
--- a/lib/test_bitmap.c
+++ b/lib/test_bitmap.c
@@ -1372,54 +1372,6 @@ static void __init test_bitmap_read_write(void)
 		test_bitmap_write_helper(pattern[pi]);
 }
 
-static void __init test_bitmap_read_perf(void)
-{
-	DECLARE_BITMAP(bitmap, TEST_BIT_LEN);
-	unsigned int cnt, nbits, i;
-	unsigned long val;
-	ktime_t time;
-
-	bitmap_fill(bitmap, TEST_BIT_LEN);
-	time = ktime_get();
-	for (cnt = 0; cnt < 5; cnt++) {
-		for (nbits = 1; nbits <= BITS_PER_LONG; nbits++) {
-			for (i = 0; i < TEST_BIT_LEN; i++) {
-				if (i + nbits > TEST_BIT_LEN)
-					break;
-				/*
-				 * Prevent the compiler from optimizing away the
-				 * bitmap_read() by using its value.
-				 */
-				WRITE_ONCE(val, bitmap_read(bitmap, i, nbits));
-			}
-		}
-	}
-	time = ktime_get() - time;
-	pr_info("Time spent in %s:\t%llu\n", __func__, time);
-}
-
-static void __init test_bitmap_write_perf(void)
-{
-	DECLARE_BITMAP(bitmap, TEST_BIT_LEN);
-	unsigned int cnt, nbits, i;
-	unsigned long val = 0xfeedface;
-	ktime_t time;
-
-	bitmap_zero(bitmap, TEST_BIT_LEN);
-	time = ktime_get();
-	for (cnt = 0; cnt < 5; cnt++) {
-		for (nbits = 1; nbits <= BITS_PER_LONG; nbits++) {
-			for (i = 0; i < TEST_BIT_LEN; i++) {
-				if (i + nbits > TEST_BIT_LEN)
-					break;
-				bitmap_write(bitmap, val, i, nbits);
-			}
-		}
-	}
-	time = ktime_get() - time;
-	pr_info("Time spent in %s:\t%llu\n", __func__, time);
-}
-
 #undef TEST_BIT_LEN
 
 static void __init selftest(void)
@@ -1440,8 +1392,6 @@ static void __init selftest(void)
 	test_bitmap_print_buf();
 	test_bitmap_const_eval();
 	test_bitmap_read_write();
-	test_bitmap_read_perf();
-	test_bitmap_write_perf();
 
 	test_find_nth_bit();
 	test_for_each_set_bit();

-- 
2.52.0