From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753248AbdKNG5s (ORCPT ); Tue, 14 Nov 2017 01:57:48 -0500 Received: from mail-pf0-f196.google.com ([209.85.192.196]:43778 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752210AbdKNG5n (ORCPT ); Tue, 14 Nov 2017 01:57:43 -0500 X-Google-Smtp-Source: AGs4zMab8mxovVCtDZtKVw9cYUj8WeBQVlngW4Ruh6ZJfN2Q0d/PPvmaRS9jLIHmkNs3M9QOqKkk3g== From: Rakib Mullick To: linux-kernel@vger.kernel.org Cc: Andrew Morton , Rasmus Villemoes , Matthew Wilcox , Yury Norov , Mauro Carvalho Chehab Subject: [PATCH] lib: Avoid redundant sizeof checking in __bitmap_weight() calculation. Date: Tue, 14 Nov 2017 12:57:31 +0600 Message-Id: <20171114065731.3602-1-rakib.mullick@gmail.com> X-Mailer: git-send-email 2.9.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, during __bitmap_weight() calculation hweight_long() is used. Inside a hweight_long() a check has been made to figure out whether a hweight32() or hweight64() version to use. However, it's unnecessary to do it in case of __bitmap_weight() calculation inside the loop. We can detect whether to use hweight32() or hweight64() upfront and call respective function directly. It also reduces the vmlinux size. Before the patch: text data bss dec hex filename 12901332 7798930 14541816 35242078 219c05e vmlinux After the patch: text data bss dec hex filename 12901331 7798930 14541816 35242077 219c05d vmlinux Signed-off-by: Rakib Mullick Cc: Andrew Morton Cc: Rasmus Villemoes Cc: Matthew Wilcox Cc: Yury Norov Cc: Mauro Carvalho Chehab --- Patch was created against torvald's tree (commit 43ff2f4db9d0f764). lib/bitmap.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/lib/bitmap.c b/lib/bitmap.c index d8f0c09..552096f 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -241,10 +241,15 @@ EXPORT_SYMBOL(__bitmap_subset); int __bitmap_weight(const unsigned long *bitmap, unsigned int bits) { unsigned int k, lim = bits/BITS_PER_LONG; - int w = 0; - - for (k = 0; k < lim; k++) - w += hweight_long(bitmap[k]); + int w = 0, is32 = sizeof(bitmap[0]) ? 1 : 0; + + if (is32) { + for (k = 0; k < lim; k++) + w += hweight32(bitmap[k]); + } else { + for (k = 0; k < lim; k++) + w += hweight64(bitmap[k]); + } if (bits % BITS_PER_LONG) w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits)); -- 2.9.3