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a89107c047
In commit 53cdc1cb29 ("drivers/base/memory.c: indicate all memory blocks
as removable") we changed the output of the "removable" property of memory
devices to return "1" if and only if the kernel supports memory offlining.
Let's update documentation, stating that the interface is legacy. Also
update documentation of the "state" property and "valid_zones" properties.
Link: https://lkml.kernel.org/r/20210201181347.13262-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
113 lines
4.3 KiB
Plaintext
113 lines
4.3 KiB
Plaintext
What: /sys/devices/system/memory
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Date: June 2008
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Contact: Badari Pulavarty <pbadari@us.ibm.com>
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Description:
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The /sys/devices/system/memory contains a snapshot of the
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internal state of the kernel memory blocks. Files could be
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added or removed dynamically to represent hot-add/remove
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operations.
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Users: hotplug memory add/remove tools
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http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
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What: /sys/devices/system/memory/memoryX/removable
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Date: June 2008
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Contact: Badari Pulavarty <pbadari@us.ibm.com>
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Description:
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The file /sys/devices/system/memory/memoryX/removable is a
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legacy interface used to indicated whether a memory block is
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likely to be offlineable or not. Newer kernel versions return
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"1" if and only if the kernel supports memory offlining.
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Users: hotplug memory remove tools
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http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
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lsmem/chmem part of util-linux
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What: /sys/devices/system/memory/memoryX/phys_device
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Date: September 2008
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Contact: Badari Pulavarty <pbadari@us.ibm.com>
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Description:
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The file /sys/devices/system/memory/memoryX/phys_device
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is read-only; it is a legacy interface only ever used on s390x
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to expose the covered storage increment.
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Users: Legacy s390-tools lsmem/chmem
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What: /sys/devices/system/memory/memoryX/phys_index
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Date: September 2008
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Contact: Badari Pulavarty <pbadari@us.ibm.com>
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Description:
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The file /sys/devices/system/memory/memoryX/phys_index
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is read-only and contains the section ID in hexadecimal
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which is equivalent to decimal X contained in the
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memory section directory name.
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What: /sys/devices/system/memory/memoryX/state
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Date: September 2008
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Contact: Badari Pulavarty <pbadari@us.ibm.com>
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Description:
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The file /sys/devices/system/memory/memoryX/state
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is read-write. When read, it returns the online/offline
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state of the memory block. When written, root can toggle
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the online/offline state of a memory block using the following
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commands::
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# echo online > /sys/devices/system/memory/memoryX/state
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# echo offline > /sys/devices/system/memory/memoryX/state
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On newer kernel versions, advanced states can be specified
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when onlining to select a target zone: "online_movable"
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selects the movable zone. "online_kernel" selects the
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applicable kernel zone (DMA, DMA32, or Normal). However,
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after successfully setting one of the advanced states,
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reading the file will return "online"; the zone information
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can be obtained via "valid_zones" instead.
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While onlining is unlikely to fail, there are no guarantees
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that offlining will succeed. Offlining is more likely to
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succeed if "valid_zones" indicates "Movable".
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Users: hotplug memory remove tools
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http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
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What: /sys/devices/system/memory/memoryX/valid_zones
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Date: July 2014
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Contact: Zhang Zhen <zhenzhang.zhang@huawei.com>
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Description:
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The file /sys/devices/system/memory/memoryX/valid_zones is
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read-only.
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For online memory blocks, it returns in which zone memory
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provided by a memory block is managed. If multiple zones
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apply (not applicable for hotplugged memory), "None" is returned
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and the memory block cannot be offlined.
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For offline memory blocks, it returns by which zone memory
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provided by a memory block can be managed when onlining.
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The first returned zone ("default") will be used when setting
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the state of an offline memory block to "online". Only one of
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the kernel zones (DMA, DMA32, Normal) is applicable for a single
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memory block.
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What: /sys/devices/system/memoryX/nodeY
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Date: October 2009
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Contact: Linux Memory Management list <linux-mm@kvack.org>
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Description:
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When CONFIG_NUMA is enabled, a symbolic link that
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points to the corresponding NUMA node directory.
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For example, the following symbolic link is created for
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memory section 9 on node0:
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/sys/devices/system/memory/memory9/node0 -> ../../node/node0
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What: /sys/devices/system/node/nodeX/memoryY
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Date: September 2008
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Contact: Gary Hade <garyhade@us.ibm.com>
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Description:
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When CONFIG_NUMA is enabled
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/sys/devices/system/node/nodeX/memoryY is a symbolic link that
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points to the corresponding /sys/devices/system/memory/memoryY
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memory section directory. For example, the following symbolic
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link is created for memory section 9 on node0.
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/sys/devices/system/node/node0/memory9 -> ../../memory/memory9
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