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Mon, 16 Dec 2019 10:18:15 +0000 (UTC) Received: from [10.72.12.47] (ovpn-12-47.pek2.redhat.com [10.72.12.47]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9B5BD5C28C; Mon, 16 Dec 2019 10:17:43 +0000 (UTC) Subject: Re: [PATCH v15 4/7] mm: Introduce Reported pages To: Alexander Duyck , kvm@vger.kernel.org, mst@redhat.com, linux-kernel@vger.kernel.org, willy@infradead.org, mhocko@kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, mgorman@techsingularity.net, vbabka@suse.cz Cc: yang.zhang.wz@gmail.com, konrad.wilk@oracle.com, david@redhat.com, pagupta@redhat.com, riel@surriel.com, lcapitulino@redhat.com, dave.hansen@intel.com, wei.w.wang@intel.com, aarcange@redhat.com, pbonzini@redhat.com, dan.j.williams@intel.com, alexander.h.duyck@linux.intel.com, osalvador@suse.de References: <20191205161928.19548.41654.stgit@localhost.localdomain> <20191205162238.19548.68238.stgit@localhost.localdomain> From: Nitesh Narayan Lal Openpgp: preference=signencrypt Autocrypt: addr=nitesh@redhat.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20191205162238.19548.68238.stgit@localhost.localdomain> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 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 12/5/19 11:22 AM, Alexander Duyck wrote: > From: Alexander Duyck > > In order to pave the way for free page reporting in virtualized > environments we will need a way to get pages out of the free lists and > identify those pages after they have been returned. To accomplish this,= > this patch adds the concept of a Reported Buddy, which is essentially > meant to just be the Uptodate flag used in conjunction with the Buddy > page type. [...] > +enum { > + PAGE_REPORTING_IDLE =3D 0, > + PAGE_REPORTING_REQUESTED, > + PAGE_REPORTING_ACTIVE > +}; > + > +/* request page reporting */ > +static void > +__page_reporting_request(struct page_reporting_dev_info *prdev) > +{ > + unsigned int state; > + > + /* Check to see if we are in desired state */ > + state =3D atomic_read(&prdev->state); > + if (state =3D=3D PAGE_REPORTING_REQUESTED) > + return; > + > + /* > + * If reporting is already active there is nothing we need to do. > + * Test against 0 as that represents PAGE_REPORTING_IDLE. > + */ > + state =3D atomic_xchg(&prdev->state, PAGE_REPORTING_REQUESTED); > + if (state !=3D PAGE_REPORTING_IDLE) > + return; > + > + /* > + * Delay the start of work to allow a sizable queue to build. For > + * now we are limiting this to running no more than once every > + * couple of seconds. > + */ > + schedule_delayed_work(&prdev->work, PAGE_REPORTING_DELAY); > +} > + I think you recently switched to using an atomic variable for maintaining= page reporting status as I was doing in v12. Which is good, as we will not have a disagreement on it now. On a side note, apologies for not getting involved actively in the discussions/reviews as I am on PTO. --=20 Nitesh