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[195.135.220.15]) by mx.google.com with ESMTPS id t25si363349ejt.245.2019.03.12.06.38.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 12 Mar 2019 06:38:18 -0700 (PDT) Received-SPF: softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org 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) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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