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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 72028C10F00 for ; Tue, 12 Mar 2019 16:44:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3C2CB214AE for ; Tue, 12 Mar 2019 16:44:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1552409066; bh=z0KMNbw0qKXUa8yJfspk5oKOih4joxqpNz7O21hXz+M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=oARmQ6PNlK6jKF48gR7FJkJwUiNhVlbpp6Lu+GO61TuyMt31XwPZi/Ap7+gQbzQHw aW5M51FSirWQtzESaUGEjXbUV+5eKrfGk6aHFFz1yO82dzxDrteL0wmq9INH1H0pCG MyvriJbywoyuRZ4fBe4eZ/y16XMOidv5PPm7A8ms= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726753AbfCLQoY (ORCPT ); Tue, 12 Mar 2019 12:44:24 -0400 Received: from mx2.suse.de ([195.135.220.15]:57802 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726329AbfCLQoY (ORCPT ); Tue, 12 Mar 2019 12:44:24 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 4E0F8AF0C; Tue, 12 Mar 2019 16:44:23 +0000 (UTC) Date: Tue, 12 Mar 2019 17:44:22 +0100 From: Michal Hocko To: Yafang Shao Cc: Vlastimil Babka , Souptick Joarder , Andrew Morton , Linux MM , LKML , shaoyafang@didiglobal.com Subject: Re: [PATCH] mm: compaction: some tracepoints should be defined only when CONFIG_COMPACTION is set Message-ID: <20190312164422.GD5721@dhcp22.suse.cz> References: <1551501538-4092-1-git-send-email-laoar.shao@gmail.com> <1551501538-4092-2-git-send-email-laoar.shao@gmail.com> <20190312161803.GC5721@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 13-03-19 00:29:57, Yafang Shao wrote: > On Wed, Mar 13, 2019 at 12:18 AM Michal Hocko wrote: > > > > On Sat 02-03-19 12:38:58, Yafang Shao wrote: > > > Only mm_compaction_isolate_{free, migrate}pages may be used when > > > CONFIG_COMPACTION is not set. > > > All others are used only when CONFIG_COMPACTION is set. > > > > Why is this an improvement? > > > > After this change, if CONFIG_COMPACTION is not set, the tracepoints > that only work when CONFIG_COMPACTION is set will not be exposed to > the usespace. > Without this change, they will always be expose in debugfs no matter > CONFIG_COMPACTION is set or not. And this is exactly something that the changelog should mention. I wasn't aware that we do export tracepoints even when they are not used by any code path. This whole macro based programming is just a black magic. -- Michal Hocko SUSE Labs