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=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 6A7A5C49ED9 for ; Thu, 12 Sep 2019 10:24:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 38EB1214AE for ; Thu, 12 Sep 2019 10:24:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="rjY82Sy3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731082AbfILKY1 (ORCPT ); Thu, 12 Sep 2019 06:24:27 -0400 Received: from mail-ed1-f66.google.com ([209.85.208.66]:34879 "EHLO mail-ed1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730811AbfILKY1 (ORCPT ); Thu, 12 Sep 2019 06:24:27 -0400 Received: by mail-ed1-f66.google.com with SMTP id f24so5847399edv.2 for ; Thu, 12 Sep 2019 03:24:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=+mmfaBX0Np9W/b7Q5MqD32lbNina1cQ/FOr9Xbx+2SA=; b=rjY82Sy3etyc/lURHAAH5Zl+/VTkVL1QfiSGIjGFzaoW/tFRFM+zEYupBdTECALHrG yPnD/zet+9v/0zbzm/E5VjxIC4kHBGoI6fG6y3ZudVWE1Fqr5jUEFHOhmpHGUgJBjFLR Pp4qZYYyCBsVXmvAX8dVxq7xFDjWJd+exfdSoleHOrbAKfryXx1FyZtARD7dR7tAJFzo JrefYLyjWx+Ptmb0NQyHMPY02QIUK5RaU1NoX/BBPIIVc7yZpU9xVdpA7vqiSPpdXXbt d5OJ8VA03djK7lmxCv6oPg+S+/UFNoBoSlbJXwZ5azlQ2uo9F1xXDa4+5x33RZHpoQkO TV/w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=+mmfaBX0Np9W/b7Q5MqD32lbNina1cQ/FOr9Xbx+2SA=; b=E7iKzuaKHIaemnUi+yl9RTpAKb1WBEUx3+zqiWDxXZqH617bQ5fiYFp/2OAe4rPXmB GNk2fDgsKVtY5VAl1s5Yip1hjKnzGjPY61BRqxEGWb4dRbYrxlhdPX2GRWdQMovNIbCR P6xc6uTiaVESgdNMhVNvqpjfQlQEf7unJUT0ErY2Jw+6QABG0jUgEJ1F1UOpgwok8sx2 Rh3dOkmi7EitwzNVUQvP7PyLLdyt2MJmd6weP8hpSsCbsrVA6/f0VeVJhPWIc87oU9xS xHgPyHFY7phlTvGHc2T2EIgQJnBLU8PJg3N2R9K3kT3ve8BGOWi7i6d4fsHlQUPy9cq2 rA3Q== X-Gm-Message-State: APjAAAUYZMHmNDJ/COZ/yhl1/N/z7qyxlMHcP9PnQMNtFI8csjHxTWP9 ZkcyyVcQ7/UlOSo15H7BnJcQfw== X-Google-Smtp-Source: APXvYqxqQuNiTjkjaC8Hs02PHF+LHAOwtw4KJLDqhBlQ3F6XmLygJAqZUw/cEZVOIq4hY2vxi9be2Q== X-Received: by 2002:a50:8961:: with SMTP id f30mr40528236edf.144.1568283865271; Thu, 12 Sep 2019 03:24:25 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id qt5sm2710889ejb.11.2019.09.12.03.24.24 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 12 Sep 2019 03:24:24 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id 04633100B4A; Thu, 12 Sep 2019 13:24:26 +0300 (+03) Date: Thu, 12 Sep 2019 13:24:25 +0300 From: "Kirill A. Shutemov" To: Michal Hocko Cc: Alexander Duyck , Alexander Duyck , virtio-dev@lists.oasis-open.org, kvm list , "Michael S. Tsirkin" , Catalin Marinas , David Hildenbrand , Dave Hansen , LKML , Matthew Wilcox , linux-mm , Andrew Morton , will@kernel.org, linux-arm-kernel@lists.infradead.org, Oscar Salvador , Yang Zhang , Pankaj Gupta , Konrad Rzeszutek Wilk , Nitesh Narayan Lal , Rik van Riel , lcapitulino@redhat.com, "Wang, Wei W" , Andrea Arcangeli , ying.huang@intel.com, Paolo Bonzini , Dan Williams , Fengguang Wu , "Kirill A. Shutemov" , Mel Gorman , Vlastimil Babka Subject: Re: [PATCH v9 0/8] stg mail -e --version=v9 \ Message-ID: <20190912102425.wzhhe6ygfgg64sma@box> References: <20190907172225.10910.34302.stgit@localhost.localdomain> <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190912091925.GM4023@dhcp22.suse.cz> User-Agent: NeoMutt/20180716 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org 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. -- Kirill A. Shutemov