From: Oscar Salvador <osalvador@suse.de>
To: Dan Williams <dan.j.williams@intel.com>, akpm@linux-foundation.org
Cc: Michal Hocko <mhocko@suse.com>, Vlastimil Babka <vbabka@suse.cz>,
Logan Gunthorpe <logang@deltatee.com>,
Pavel Tatashin <pasha.tatashin@soleen.com>, Qian Cai <cai@lca.pw>,
Jane Chu <jane.chu@oracle.com>,
linux-mm@kvack.org, linux-nvdimm@lists.01.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v10 03/13] mm/sparsemem: Add helpers track active portions of a section at boot
Date: Mon, 24 Jun 2019 19:57:55 +0200 [thread overview]
Message-ID: <1561399075.3073.6.camel@suse.de> (raw)
In-Reply-To: <156092350874.979959.18185938451405518285.stgit@dwillia2-desk3.amr.corp.intel.com>
On Tue, 2019-06-18 at 22:51 -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 either determine that
> the
> section is an "early section", or 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() / early_section()
> data, so the incremental performance overhead to pfn_valid() should
> be
> negligible.
>
> The rationale for using early_section() to short-ciruit the
> subsection_map check is that there are legacy code paths that use
> pfn_valid() at section granularity before validating the pfn against
> pgdat data. So, the early_section() check allows those traditional
> assumptions to persist while also permitting subsection_map to tell
> the
> truth for purposes of populating the unused portions of early
> sections
> with PMEM and other ZONE_DEVICE mappings.
>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Logan Gunthorpe <logang@deltatee.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
> Reported-by: Qian Cai <cai@lca.pw>
> Tested-by: Jane Chu <jane.chu@oracle.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
--
Oscar Salvador
SUSE L3
next prev parent reply other threads:[~2019-06-24 17:58 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-19 5:51 [PATCH v10 00/13] mm: Sub-section memory hotplug support Dan Williams
2019-06-19 5:51 ` [PATCH v10 01/13] mm/sparsemem: Introduce struct mem_section_usage Dan Williams
2019-06-19 5:51 ` [PATCH v10 02/13] mm/sparsemem: Introduce a SECTION_IS_EARLY flag Dan Williams
2019-06-24 17:54 ` Oscar Salvador
2019-06-19 5:51 ` [PATCH v10 03/13] mm/sparsemem: Add helpers track active portions of a section at boot Dan Williams
2019-06-24 17:57 ` Oscar Salvador [this message]
2019-06-19 5:51 ` [PATCH v10 04/13] mm/hotplug: Prepare shrink_{zone, pgdat}_span for sub-section removal Dan Williams
2019-06-19 5:52 ` [PATCH v10 05/13] mm/sparsemem: Convert kmalloc_section_memmap() to populate_section_memmap() Dan Williams
2019-06-24 18:00 ` Oscar Salvador
2019-06-19 5:52 ` [PATCH v10 06/13] mm/hotplug: Kill is_dev_zone() usage in __remove_pages() Dan Williams
2019-06-19 5:52 ` [PATCH v10 07/13] mm: Kill is_dev_zone() helper Dan Williams
2019-06-19 5:52 ` [PATCH v10 08/13] mm/sparsemem: Prepare for sub-section ranges Dan Williams
2019-06-20 10:31 ` David Hildenbrand
2019-06-20 16:19 ` Dan Williams
2019-06-20 16:35 ` David Hildenbrand
2019-06-20 16:56 ` Dan Williams
2019-06-24 18:05 ` Oscar Salvador
2019-06-19 5:52 ` [PATCH v10 09/13] mm/sparsemem: Support sub-section hotplug Dan Williams
2019-06-24 20:45 ` Oscar Salvador
2019-06-19 5:52 ` [PATCH v10 10/13] mm: Document ZONE_DEVICE memory-model implications Dan Williams
2019-06-20 12:30 ` Mike Rapoport
2019-06-19 5:52 ` [PATCH v10 11/13] mm/devm_memremap_pages: Enable sub-section remap Dan Williams
2019-06-19 5:52 ` [PATCH v10 12/13] libnvdimm/pfn: Fix fsdax-mode namespace info-block zero-fields Dan Williams
2019-06-19 16:30 ` Aneesh Kumar K.V
2019-06-19 17:06 ` Dan Williams
2019-06-19 5:52 ` [PATCH v10 13/13] libnvdimm/pfn: Stop padding pmem namespaces to section alignment Dan Williams
2019-06-20 12:30 ` [PATCH v10 00/13] mm: Sub-section memory hotplug support Aneesh Kumar K.V
2019-06-20 16:30 ` Dan Williams
2019-06-20 17:00 ` Oscar Salvador
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