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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham 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 D0902C46470 for ; Thu, 6 Jun 2019 16:55:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AA9C620868 for ; Thu, 6 Jun 2019 16:55:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729853AbfFFQzq (ORCPT ); Thu, 6 Jun 2019 12:55:46 -0400 Received: from mx2.suse.de ([195.135.220.15]:55242 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728718AbfFFQzq (ORCPT ); Thu, 6 Jun 2019 12:55:46 -0400 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) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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