From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751581AbdFGO3o (ORCPT ); Wed, 7 Jun 2017 10:29:44 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:54405 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751190AbdFGO3g (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 3/3] bitmap: Use memcmp optimisation in more situations Date: Wed, 7 Jun 2017 07:29:24 -0700 Message-Id: <20170607142924.28552-4-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 Commit 7dd968163f ("bitmap: bitmap_equal memcmp optimization") was rather more restrictive than necessary; we can use memcmp() to implement bitmap_equal() as long as the number of bits can be proved to be a multiple of 8. And architectures other than s390 may be able to make good use of this optimisation. Signed-off-by: Matthew Wilcox --- include/linux/bitmap.h | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index 0b3e4452b054..26244e0098f0 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -266,10 +266,8 @@ static inline int bitmap_equal(const unsigned long *src1, { if (small_const_nbits(nbits)) return !((*src1 ^ *src2) & BITMAP_LAST_WORD_MASK(nbits)); -#ifdef CONFIG_S390 - if (__builtin_constant_p(nbits) && (nbits % BITS_PER_LONG) == 0) + if (__builtin_constant_p(nbits & 7) && IS_ALIGNED(nbits, 8)) return !memcmp(src1, src2, nbits / 8); -#endif return __bitmap_equal(src1, src2, nbits); } -- 2.11.0