diff mbox series

ARM: mm: use bitmap_zero() API

Message ID 202305061635221161194@zte.com.cn
State New
Headers
Series ARM: mm: use bitmap_zero() API |

Commit Message

ye.xingchen@zte.com.cn May 6, 2023, 8:35 a.m. UTC 
  From: Ye Xingchen <ye.xingchen@zte.com.cn>

bitmap_zero() is faster than bitmap_clear(), so use bitmap_zero()
instead of bitmap_clear().

Signed-off-by: Ye Xingchen <ye.xingchen@zte.com.cn>
---
 arch/arm/mm/context.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Russell King (Oracle) May 6, 2023, 10:35 a.m. UTC | #1 
On Sat, May 06, 2023 at 04:35:22PM +0800, ye.xingchen@zte.com.cn wrote:
> From: Ye Xingchen <ye.xingchen@zte.com.cn>
> 
> bitmap_zero() is faster than bitmap_clear(), so use bitmap_zero()
> instead of bitmap_clear().

Maybe in theory, but as NUM_USER_ASIDS is a power of two (256),
and therefore both start and nbits are aigned to BITMAP_MEM_ALIGNMENT,
bitmap_clear() will call memset().

The only difference between the two are that bitmap_zero() doesn't
involve the compiler working out that it can call memset() (which
will be worked out at compile time not run time).

So, I doubt that this change makes any difference what so ever to the
generated code, and thus this change is just for change sake. In
other words, it's just useless churn.

Thanks anyway.
diff mbox series

Patch

diff --git a/arch/arm/mm/context.c b/arch/arm/mm/context.c
index 4204ffa2d104..2e95a707eb93 100644
--- a/arch/arm/mm/context.c
+++ b/arch/arm/mm/context.c
@@ -139,7 +139,7 @@  static void flush_context(unsigned int cpu)
 	u64 asid;

 	/* Update the list of reserved ASIDs and the ASID bitmap. */
-	bitmap_clear(asid_map, 0, NUM_USER_ASIDS);
+	bitmap_zero(asid_map, NUM_USER_ASIDS);
 	for_each_possible_cpu(i) {
 		asid = atomic64_xchg(&per_cpu(active_asids, i), 0);
 		/*