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 04442C10F00 for ; Tue, 12 Mar 2019 13:38:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C22632171F for ; Tue, 12 Mar 2019 13:38:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1552397900; bh=p4LcNkekg4TnXFFUzhct4tzaw9RrdasPKA47ITk6h38=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=iv4/trtRQpmtgEP03UL2kONI8BtHxkOtyH3e2uC57nHnjnWy3qb7B12W3s+IWIKtp XKtZZSTYMPf3NV/o6cUwNr7oSC3SzHoE+aIeaafQKGoLJU1GyRjBGU4wAcNdBcgDdf 1inTiNKZlToj/anMTYsjKXYQ7OETfQ8uy/WNVqIk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726765AbfCLNiT (ORCPT ); Tue, 12 Mar 2019 09:38:19 -0400 Received: from mx2.suse.de ([195.135.220.15]:50554 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725774AbfCLNiS (ORCPT ); Tue, 12 Mar 2019 09:38:18 -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 A54D5ABCF; Tue, 12 Mar 2019 13:38:17 +0000 (UTC) Date: Tue, 12 Mar 2019 14:38:16 +0100 From: Michal Hocko To: Yafang Shao Cc: Vlastimil Babka , Souptick Joarder , Andrew Morton , Linux MM , LKML , shaoyafang@didiglobal.com Subject: Re: [PATCH] mm: vmscan: show zone type in kswapd tracepoints Message-ID: <20190312133816.GR5721@dhcp22.suse.cz> References: <1551425934-28068-1-git-send-email-laoar.shao@gmail.com> <20190311084743.GX5232@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 Tue 12-03-19 19:04:43, Yafang Shao wrote: > On Mon, Mar 11, 2019 at 4:47 PM Michal Hocko wrote: > > > > On Fri 01-03-19 15:38:54, Yafang Shao wrote: > > > If we want to know the zone type, we have to check whether > > > CONFIG_ZONE_DMA, CONFIG_ZONE_DMA32 and CONFIG_HIGHMEM are set or not, > > > that's not so convenient. > > > > > > We'd better show the zone type directly. > > > > I do agree that zone number is quite PITA to process in general but do > > we really need this information in the first place? Why do we even care? > > > > Sometimes we want to know this event occurs in which zone, then we can > get the information of this zone, > for example via /proc/zoneinfo. > It could give us more information for debugging. Could you be more specific please? > > Zones are an MM internal implementation details and the more we export > > to the userspace the more we are going to argue about breaking userspace > > when touching them. So I would rather not export that information unless > > it is terribly useful. > > > > I 'm not sure whether zone type is terribly useful or not, but the > 'zid' is useless at all. > > I don't agree that Zones are MM internal. > We can get the zone type in many ways, for example /proc/zoneinfo. > > If we show this event occurs in which zone, we'd better show the zone type, > or we should drop this 'zid'. Yes, I am suggesting the later. If somebody really needs it then I would like to see a _specific_ usecase. Then we can add the proper name. -- Michal Hocko SUSE Labs