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[195.135.220.15]) by mx.google.com with ESMTPS id w27si998357ejb.220.2019.03.13.14.06.10 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 13 Mar 2019 14:06:10 -0700 (PDT) Received-SPF: softfail (google.com: domain of transitioning dave@stgolabs.net 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 dave@stgolabs.net does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=dave@stgolabs.net 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 D7F88AB71; Wed, 13 Mar 2019 21:06:09 +0000 (UTC) Date: Wed, 13 Mar 2019 14:06:03 -0700 From: Davidlohr Bueso To: Laurent Dufour Cc: lsf-pc@lists.linux-foundation.org, Linux-MM , linux-kernel@vger.kernel.org, Matthew Wilcox Subject: Re: [LSF/MM TOPIC] Using XArray to manage the VMA Message-ID: <20190313210603.fguuxu3otj5epk3q@linux-r8p5> Mail-Followup-To: Laurent Dufour , lsf-pc@lists.linux-foundation.org, Linux-MM , linux-kernel@vger.kernel.org, Matthew Wilcox References: <7da20892-f92a-68d8-4804-c72c1cb0d090@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <7da20892-f92a-68d8-4804-c72c1cb0d090@linux.ibm.com> User-Agent: NeoMutt/20180323 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 Wed, 13 Mar 2019, Laurent Dufour wrote: >If this is not too late and if there is still place available, I would >like to attend the MM track and propose a topic about using the XArray >to replace the VMA's RB tree and list. > >Using the XArray in place of the VMA's tree and list seems to be a >first step to the long way of removing/replacing the mmap_sem. So threaded (not as in threads of execution) rbtrees are another alternative to deal with the two data structure approach we currently have. Having O(1) rb_prev/next() calls allows us to basically get rid of the vma list at the cost of an extra check for each node we visit on the way down when inserting. Thanks, Davidlohr