From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751818AbdF1Pcn (ORCPT ); Wed, 28 Jun 2017 11:32:43 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:39099 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751516AbdF1Pch (ORCPT ); Wed, 28 Jun 2017 11:32:37 -0400 From: Matthew Wilcox To: linux-kernel@vger.kernel.org Cc: Andrew Morton , Martin Schwidefsky , Rasmus Villemoes , Matthew Wilcox Subject: [PATCH v2 4/4] bitmap: Use memcmp optimisation in more situations Date: Wed, 28 Jun 2017 08:32:21 -0700 Message-Id: <20170628153221.11322-5-willy@infradead.org> X-Mailer: git-send-email 2.9.4 In-Reply-To: <20170628153221.11322-1-willy@infradead.org> References: <20170628153221.11322-1-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 Acked-by: Rasmus Villemoes --- 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 c04c9d155e59..5797ca6fdfe2 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