From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753171AbbCXPYp (ORCPT ); Tue, 24 Mar 2015 11:24:45 -0400 Received: from mail-pd0-f169.google.com ([209.85.192.169]:33885 "EHLO mail-pd0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752661AbbCXPYk (ORCPT ); Tue, 24 Mar 2015 11:24:40 -0400 From: Sergey Senozhatsky To: Andrew Morton , Minchan Kim Cc: Nitin Gupta , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky , Sergey Senozhatsky Subject: [PATCH 2/2] zsmalloc: micro-optimize zs_object_copy() Date: Wed, 25 Mar 2015 00:24:47 +0900 Message-Id: <1427210687-6634-3-git-send-email-sergey.senozhatsky@gmail.com> X-Mailer: git-send-email 2.3.4.263.gf53fc38 In-Reply-To: <1427210687-6634-1-git-send-email-sergey.senozhatsky@gmail.com> References: <1427210687-6634-1-git-send-email-sergey.senozhatsky@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org A micro-optimization. Avoid additional branching and reduce (a bit) registry pressure (f.e. s_off += size; d_off += size; may be calculated twise: first for >= PAGE_SIZE check and later for offset update in "else" clause). /scripts/bloat-o-meter shows some improvement add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-10 (-10) function old new delta zs_object_copy 550 540 -10 Signed-off-by: Sergey Senozhatsky --- mm/zsmalloc.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index 7af4456..dc35328 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -1535,28 +1535,27 @@ static void zs_object_copy(unsigned long src, unsigned long dst, if (written == class->size) break; - if (s_off + size >= PAGE_SIZE) { + s_off += size; + s_size -= size; + d_off += size; + d_size -= size; + + if (s_off >= PAGE_SIZE) { kunmap_atomic(s_addr); s_page = get_next_page(s_page); BUG_ON(!s_page); s_addr = kmap_atomic(s_page); s_size = class->size - written; s_off = 0; - } else { - s_off += size; - s_size -= size; } - if (d_off + size >= PAGE_SIZE) { + if (d_off >= PAGE_SIZE) { kunmap_atomic(d_addr); d_page = get_next_page(d_page); BUG_ON(!d_page); d_addr = kmap_atomic(d_page); d_size = class->size - written; d_off = 0; - } else { - d_off += size; - d_size -= size; } } -- 2.3.4