From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f44.google.com (mail-pa0-f44.google.com [209.85.220.44]) by kanga.kvack.org (Postfix) with ESMTP id 0441A6B0070 for ; Tue, 24 Mar 2015 11:24:41 -0400 (EDT) Received: by padcy3 with SMTP id cy3so228828119pad.3 for ; Tue, 24 Mar 2015 08:24:40 -0700 (PDT) Received: from mail-pd0-x234.google.com (mail-pd0-x234.google.com. [2607:f8b0:400e:c02::234]) by mx.google.com with ESMTPS id ch12si6002890pdb.146.2015.03.24.08.24.40 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 24 Mar 2015 08:24:40 -0700 (PDT) Received: by pdnc3 with SMTP id c3so224606373pdn.0 for ; Tue, 24 Mar 2015 08:24:40 -0700 (PDT) From: 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> 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: owner-linux-mm@kvack.org List-ID: To: Andrew Morton , Minchan Kim Cc: Nitin Gupta , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky , Sergey Senozhatsky 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org