From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751630AbdFGO3r (ORCPT ); Wed, 7 Jun 2017 10:29:47 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:47812 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751072AbdFGO3g (ORCPT ); Wed, 7 Jun 2017 10:29:36 -0400 From: Matthew Wilcox To: linux-kernel@vger.kernel.org Cc: Andrew Morton , Martin Schwidefsky , Rasmus Villemoes , Matthew Wilcox Subject: [PATCH 2/3] Turn bitmap_set and bitmap_clear into memset when possible Date: Wed, 7 Jun 2017 07:29:23 -0700 Message-Id: <20170607142924.28552-3-willy@infradead.org> X-Mailer: git-send-email 2.9.3 In-Reply-To: <20170607142924.28552-1-willy@infradead.org> References: <20170607142924.28552-1-willy@infradead.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Matthew Wilcox Several callers have constant 'start' and an 'nbits' that is a multiple of 8, so we can turn them into calls to memset. We don't need the entirety of 'start' and 'nbits' to be constant, we just need to know whether they're divisible by 8. Signed-off-by: Matthew Wilcox --- include/linux/bitmap.h | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index 4e0f0c8167af..0b3e4452b054 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -319,6 +319,9 @@ static __always_inline void bitmap_set(unsigned long *map, unsigned int start, { if (__builtin_constant_p(nbits) && nbits == 1) __set_bit(start, map); + else if (__builtin_constant_p(start & 7) && IS_ALIGNED(start, 8) && + __builtin_constant_p(nbits & 7) && IS_ALIGNED(nbits, 8)) + memset(map + start / 8, 0xff, nbits / 8); else __bitmap_set(map, start, nbits); } @@ -328,6 +331,9 @@ static __always_inline void bitmap_clear(unsigned long *map, unsigned int start, { if (__builtin_constant_p(nbits) && nbits == 1) __clear_bit(start, map); + else if (__builtin_constant_p(start & 7) && IS_ALIGNED(start, 8) && + __builtin_constant_p(nbits & 7) && IS_ALIGNED(nbits, 8)) + memset(map + start / 8, 0, nbits / 8); else __bitmap_clear(map, start, nbits); } -- 2.11.0