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[195.135.220.15]) by mx.google.com with ESMTPS id j26si2234302ede.86.2019.06.06.09.55.45 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 06 Jun 2019 09:55:45 -0700 (PDT) Received-SPF: pass (google.com: domain of osalvador@suse.de designates 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=pass (google.com: domain of osalvador@suse.de designates 195.135.220.15 as permitted sender) smtp.mailfrom=osalvador@suse.de 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 4C0D2AC8E; Thu, 6 Jun 2019 16:55:45 +0000 (UTC) Date: Thu, 6 Jun 2019 18:55:42 +0200 From: Oscar Salvador To: Dan Williams Cc: akpm@linux-foundation.org, Michal Hocko , Vlastimil Babka , Logan Gunthorpe , Pavel Tatashin , Jane Chu , linux-mm@kvack.org, linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v9 02/12] mm/sparsemem: Add helpers track active portions of a section at boot Message-ID: <20190606165535.GA31194@linux> References: <155977186863.2443951.9036044808311959913.stgit@dwillia2-desk3.amr.corp.intel.com> <155977187919.2443951.8925592545929008845.stgit@dwillia2-desk3.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <155977187919.2443951.8925592545929008845.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) 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, Jun 05, 2019 at 02:57:59PM -0700, Dan Williams wrote: > Prepare for hot{plug,remove} of sub-ranges of a section by tracking a > sub-section active bitmask, each bit representing a PMD_SIZE span of the > architecture's memory hotplug section size. > > The implications of a partially populated section is that pfn_valid() > needs to go beyond a valid_section() check and read the sub-section > active ranges from the bitmask. The expectation is that the bitmask > (subsection_map) fits in the same cacheline as the valid_section() data, > so the incremental performance overhead to pfn_valid() should be > negligible. > > Cc: Michal Hocko > Cc: Vlastimil Babka > Cc: Logan Gunthorpe > Cc: Oscar Salvador > Cc: Pavel Tatashin > Tested-by: Jane Chu > Signed-off-by: Dan Williams Reviewed-by: Oscar Salvador -- Oscar Salvador SUSE L3