linux-kernel - [PATCH v1 2/2] bitmap: Optimize memset() calls

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Message-Id: <20230817165453.713353-3-andriy.shevchenko@linux.intel.com>
Date:   Thu, 17 Aug 2023 19:54:53 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Yury Norov <yury.norov@...il.com>, linux-kernel@...r.kernel.org
Cc:     Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: [PATCH v1 2/2] bitmap: Optimize memset() calls

Intead of byte memset() calls use 32- or 64-bit version depending
on the compile-time BITS_PER_LONG value.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 include/linux/bitmap.h | 16 ++++++++++++----
 lib/bitmap.c           |  4 ++--
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 2d5042d1b501..6eec4d4fd623 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -234,22 +234,30 @@ extern int bitmap_print_list_to_buf(char *buf, const unsigned long *maskp,
 
 static inline void bitmap_zero(unsigned long *dst, unsigned int nbits)
 {
-	unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
+	unsigned int len = BITS_TO_LONGS(nbits);
 
 	if (small_const_nbits(nbits))
 		*dst = 0;
 	else
-		memset(dst, 0, len);
+#if BITS_PER_LONG == 64
+		memset64((uint64_t *)dst, 0, len);
+#else
+		memset32((uint32_t *)dst, 0, len);
+#endif
 }
 
 static inline void bitmap_fill(unsigned long *dst, unsigned int nbits)
 {
-	unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
+	unsigned int len = BITS_TO_LONGS(nbits);
 
 	if (small_const_nbits(nbits))
 		*dst = ~0UL;
 	else
-		memset(dst, 0xff, len);
+#if BITS_PER_LONG == 64
+		memset64((uint64_t *)dst, GENMASK(63, 0), len);
+#else
+		memset32((uint32_t *)dst, GENMASK(31, 0), len);
+#endif
 }
 
 static inline void bitmap_copy(unsigned long *dst, const unsigned long *src,
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 935e0f96e785..df0fb37a5732 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -128,7 +128,7 @@ void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
 		dst[k] = lower | upper;
 	}
 	if (off)
-		memset(&dst[lim - off], 0, off*sizeof(unsigned long));
+		bitmap_zero(&dst[lim - off], off);
 }
 EXPORT_SYMBOL(__bitmap_shift_right);
 
@@ -166,7 +166,7 @@ void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
 		dst[k + off] = lower | upper;
 	}
 	if (off)
-		memset(dst, 0, off*sizeof(unsigned long));
+		bitmap_zero(dst, off);
 }
 EXPORT_SYMBOL(__bitmap_shift_left);
 
-- 
2.40.0.1.gaa8946217a0b