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[209.132.183.28]) by mx.google.com with ESMTPS id 32si3911344qvr.213.2019.06.26.02.12.59 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 26 Jun 2019 02:12:59 -0700 (PDT) Received-SPF: pass (google.com: domain of david@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of david@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E4707307D863; Wed, 26 Jun 2019 09:12:52 +0000 (UTC) Received: from [10.36.116.174] (ovpn-116-174.ams2.redhat.com [10.36.116.174]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8B0AA5D9D6; Wed, 26 Jun 2019 09:12:36 +0000 (UTC) Subject: Re: [PATCH v1 0/6] mm / virtio: Provide support for paravirtual waste page treatment To: Christophe de Dinechin Cc: Alexander Duyck , nitesh@redhat.com, kvm@vger.kernel.org, mst@redhat.com, dave.hansen@intel.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, yang.zhang.wz@gmail.com, pagupta@redhat.com, riel@surriel.com, konrad.wilk@oracle.com, lcapitulino@redhat.com, wei.w.wang@intel.com, aarcange@redhat.com, pbonzini@redhat.com, dan.j.williams@intel.com, alexander.h.duyck@linux.intel.com References: <20190619222922.1231.27432.stgit@localhost.localdomain> <7hmui42017.fsf@turbo.dinechin.lan> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <7hmui42017.fsf@turbo.dinechin.lan> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Wed, 26 Jun 2019 09:12:55 +0000 (UTC) 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 26.06.19 11:01, Christophe de Dinechin wrote: > > David Hildenbrand writes: > >> On 20.06.19 00:32, Alexander Duyck wrote: >>> This series provides an asynchronous means of hinting to a hypervisor >>> that a guest page is no longer in use and can have the data associated >>> with it dropped. To do this I have implemented functionality that allows >>> for what I am referring to as waste page treatment. >>> >>> I have based many of the terms and functionality off of waste water >>> treatment, the idea for the similarity occurred to me after I had reached >>> the point of referring to the hints as "bubbles", as the hints used the >>> same approach as the balloon functionality but would disappear if they >>> were touched, as a result I started to think of the virtio device as an >>> aerator. The general idea with all of this is that the guest should be >>> treating the unused pages so that when they end up heading "downstream" >>> to either another guest, or back at the host they will not need to be >>> written to swap. >>> >>> When the number of "dirty" pages in a given free_area exceeds our high >>> water mark, which is currently 32, we will schedule the aeration task to >>> start going through and scrubbing the zone. While the scrubbing is taking >>> place a boundary will be defined that we use to seperate the "aerated" >>> pages from the "dirty" ones. We use the ZONE_AERATION_ACTIVE bit to flag >>> when these boundaries are in place. >> >> I still *detest* the terminology, sorry. Can't you come up with a >> simpler terminology that makes more sense in the context of operating >> systems and pages we want to hint to the hypervisor? (that is the only >> use case you are using it for so far) > > FWIW, I thought the terminology made sense, in particular given the analogy > with the balloon driver. Operating systems in general, and Linux in > particular, already use tons of analogy-supported terminology. In > particular, a "waste page treatment" terminology is not very far from > the very common "garbage collection" or "scrubbing" wordings. I would find > "hinting" much less specific. for example. > > Usually, the phrases that stick are somewhat unique while providing a > useful analogy to server as a reminder of what the thing actually > does. IMHO, it's the case here on both fronts, so I like it. While something like "waste pages" make sense, "aeration" is far out of my comfort zone. An analogy is like a joke. If you have to explain it, it's not that good. (see, that was a good analogy ;) ). -- Thanks, David / dhildenb