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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=no 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 9A556C4CECB for ; Thu, 12 Sep 2019 11:12:11 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6D529214DA for ; Thu, 12 Sep 2019 11:12:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="FWvhShGW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6D529214DA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=hTIfaUU+q9YQA/Y61CjniYEXzn2WpDlg5/8pJ7oEAkc=; b=FWvhShGWKkWCtx B1xF3CXKEGUiVrafvCjj2nGH0pApapoHe8PQnPi34aosTzt5Luyxg14P+l6TK3/RgtvuPDjWNEkMR JULqYb2dssLm/WtL4EcrUnuw1SAj879QRp0FCskS5AX42dqoBA5UujfjvXcrKnNhRMi2YYMMiZDmU /4akD+GrvU8Sfc3WqWyd+w5cUz9CNjEvSCWBJdNUwM+LBdu4Q6Nkv2enTRmWS/6qO9EK3+iL8N81p cUzQe+qf1nsz8b+S+/klR0l47iBnO4HK2WH9tOGB/u4xQaf4x6rhzveWLxKXRupv2ubOGFplhGhYQ JlWrRfHdZNcr1b2TIqkQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.2 #3 (Red Hat Linux)) id 1i8N14-0003w8-Pj; Thu, 12 Sep 2019 11:11:58 +0000 Received: from mx2.suse.de ([195.135.220.15] helo=mx1.suse.de) by bombadil.infradead.org with esmtps (Exim 4.92.2 #3 (Red Hat Linux)) id 1i8N11-0003vP-1H for linux-arm-kernel@lists.infradead.org; Thu, 12 Sep 2019 11:11:56 +0000 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 1AB9AB764; Thu, 12 Sep 2019 11:11:52 +0000 (UTC) Date: Thu, 12 Sep 2019 13:11:50 +0200 From: Michal Hocko To: "Kirill A. Shutemov" Subject: Re: [PATCH v9 0/8] stg mail -e --version=v9 \ Message-ID: <20190912111150.GQ4023@dhcp22.suse.cz> References: <20190910124209.GY2063@dhcp22.suse.cz> <20190910144713.GF2063@dhcp22.suse.cz> <20190910175213.GD4023@dhcp22.suse.cz> <1d7de9f9f4074f67c567dbb4cc1497503d739e30.camel@linux.intel.com> <20190911113619.GP4023@dhcp22.suse.cz> <20190912091925.GM4023@dhcp22.suse.cz> <20190912102425.wzhhe6ygfgg64sma@box> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190912102425.wzhhe6ygfgg64sma@box> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190912_041155_373733_3608B6F5 X-CRM114-Status: GOOD ( 21.95 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Yang Zhang , Pankaj Gupta , kvm list , "Michael S. Tsirkin" , Catalin Marinas , Alexander Duyck , lcapitulino@redhat.com, linux-mm , Alexander Duyck , will@kernel.org, Andrea Arcangeli , virtio-dev@lists.oasis-open.org, David Hildenbrand , Matthew Wilcox , "Wang, Wei W" , Mel Gorman , ying.huang@intel.com, Rik van Riel , Vlastimil Babka , Dan Williams , linux-arm-kernel@lists.infradead.org, Oscar Salvador , Nitesh Narayan Lal , Konrad Rzeszutek Wilk , Dave Hansen , LKML , Paolo Bonzini , Andrew Morton , Fengguang Wu , "Kirill A. Shutemov" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu 12-09-19 13:24:25, Kirill A. Shutemov wrote: > On Thu, Sep 12, 2019 at 11:19:25AM +0200, Michal Hocko wrote: > > On Wed 11-09-19 08:12:03, Alexander Duyck wrote: > > > On Wed, Sep 11, 2019 at 4:36 AM Michal Hocko wrote: > > > > > > > > On Tue 10-09-19 14:23:40, Alexander Duyck wrote: > > > > [...] > > > > > We don't put any limitations on the allocator other then that it needs to > > > > > clean up the metadata on allocation, and that it cannot allocate a page > > > > > that is in the process of being reported since we pulled it from the > > > > > free_list. If the page is a "Reported" page then it decrements the > > > > > reported_pages count for the free_area and makes sure the page doesn't > > > > > exist in the "Boundary" array pointer value, if it does it moves the > > > > > "Boundary" since it is pulling the page. > > > > > > > > This is still a non-trivial limitation on the page allocation from an > > > > external code IMHO. I cannot give any explicit reason why an ordering on > > > > the free list might matter (well except for page shuffling which uses it > > > > to make physical memory pattern allocation more random) but the > > > > architecture seems hacky and dubious to be honest. It shoulds like the > > > > whole interface has been developed around a very particular and single > > > > purpose optimization. > > > > > > How is this any different then the code that moves a page that will > > > likely be merged to the tail though? > > > > I guess you are referring to the page shuffling. If that is the case > > then this is an integral part of the allocator for a reason and it is > > very well obvious in the code including the consequences. I do not > > really like an idea of hiding similar constrains behind a generic > > looking feature which is completely detached from the allocator and so > > any future change of the allocator might subtly break it. > > I don't necessary follow why shuffling is more integral to page allocator > than reporting would be. It's next to shutffle.c under mm/ and integrated > in a simillar way. The main difference from my understanding is that the page reporting is a more generic looking feature which might grow different users over time yet there is a hardcoded set of restrictions to the allocator. Page shuffling is an integral part of the allocator without any other visibility outside. -- Michal Hocko SUSE Labs _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel