From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 15A36C433E6 for ; Mon, 31 Aug 2020 03:11:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF8E220720 for ; Mon, 31 Aug 2020 03:11:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727848AbgHaDLN (ORCPT ); Sun, 30 Aug 2020 23:11:13 -0400 Received: from out30-57.freemail.mail.aliyun.com ([115.124.30.57]:41464 "EHLO out30-57.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726573AbgHaDLM (ORCPT ); Sun, 30 Aug 2020 23:11:12 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R161e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e07425;MF=richard.weiyang@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0U7JHBzW_1598843468; Received: from localhost(mailfrom:richard.weiyang@linux.alibaba.com fp:SMTPD_---0U7JHBzW_1598843468) by smtp.aliyun-inc.com(127.0.0.1); Mon, 31 Aug 2020 11:11:08 +0800 From: Wei Yang To: rostedt@goodmis.org, mingo@redhat.com Cc: linux-kernel@vger.kernel.org, Wei Yang Subject: [PATCH 4/6] ftrace: simplify the calculation of page number for ftrace_page->records Date: Mon, 31 Aug 2020 11:11:02 +0800 Message-Id: <20200831031104.23322-5-richard.weiyang@linux.alibaba.com> X-Mailer: git-send-email 2.20.1 (Apple Git-117) In-Reply-To: <20200831031104.23322-1-richard.weiyang@linux.alibaba.com> References: <20200831031104.23322-1-richard.weiyang@linux.alibaba.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Based on the following two reasones, we could simplify the calculation: - If the number after roundup count is not power of 2, we would definitely have more than 1 empty page with a higher order. - get_count_order() just return current order, so one lower order could meet the requirement. The calculation could be simplified by lower one order level when pages are not power of 2. Signed-off-by: Wei Yang --- kernel/trace/ftrace.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 9021e16fa079..15fcfa16895d 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -3127,18 +3127,19 @@ static int ftrace_update_code(struct module *mod, struct ftrace_page *new_pgs) static int ftrace_allocate_records(struct ftrace_page *pg, int count) { int order; - int cnt; + int pages, cnt; if (WARN_ON(!count)) return -EINVAL; - order = get_count_order(DIV_ROUND_UP(count, ENTRIES_PER_PAGE)); + pages = DIV_ROUND_UP(count, ENTRIES_PER_PAGE); + order = get_count_order(pages); /* * We want to fill as much as possible. No more than a page * may be empty. */ - while ((PAGE_SIZE << order) / ENTRY_SIZE >= count + ENTRIES_PER_PAGE) + if (!is_power_of_2(pages)) order--; again: -- 2.20.1 (Apple Git-117)