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=-9.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 13DF5C4727D for ; Tue, 6 Oct 2020 14:35:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B99D220866 for ; Tue, 6 Oct 2020 14:35:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726695AbgJFOfV (ORCPT ); Tue, 6 Oct 2020 10:35:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:52504 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726617AbgJFOfO (ORCPT ); Tue, 6 Oct 2020 10:35:14 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A67B3208B8; Tue, 6 Oct 2020 14:35:13 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.94) (envelope-from ) id 1kPo3c-002zFc-K0; Tue, 06 Oct 2020 10:35:12 -0400 Message-ID: <20201006143512.497217762@goodmis.org> User-Agent: quilt/0.66 Date: Tue, 06 Oct 2020 10:34:58 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Wei Yang Subject: [for-linus][PATCH 12/15] ftrace: Simplify the calculation of page number for ftrace_page->records References: <20201006143446.182666356@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Wei Yang 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. Link: https://lkml.kernel.org/r/20200831031104.23322-5-richard.weiyang@linux.alibaba.com Signed-off-by: Wei Yang Signed-off-by: Steven Rostedt (VMware) --- 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 c51a91aea1fd..c3be18b4f27b 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -3129,18 +3129,19 @@ 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: -- 2.28.0