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* [PATCH v3 0/7] mm/memory_hotplug: selective merging of system ram resources
@ 2020-09-10  9:13 David Hildenbrand
  2020-09-10  9:13 ` [PATCH v3 1/7] kernel/resource: make release_mem_region_adjustable() never fail David Hildenbrand
                   ` (6 more replies)
  0 siblings, 7 replies; 14+ messages in thread
From: David Hildenbrand @ 2020-09-10  9:13 UTC (permalink / raw)
  To: linux-kernel
  Cc: virtualization, linux-mm, linux-hyperv, xen-devel, linux-acpi,
	linux-nvdimm, linux-s390, Andrew Morton, David Hildenbrand,
	Andrew Morton, Anton Blanchard, Ard Biesheuvel, Baoquan He,
	Benjamin Herrenschmidt, Boris Ostrovsky, Christian Borntraeger,
	Eric Biederman, Greg Kroah-Hartman, Haiyang Zhang,
	Heiko Carstens, Jason Gunthorpe, Jason Wang, Juergen Gross,
	Julien Grall, Kees Cook, K. Y. Srinivasan, Len Brown

Some add_memory*() users add memory in small, contiguous memory blocks.
Examples include virtio-mem, hyper-v balloon, and the XEN balloon.

This can quickly result in a lot of memory resources, whereby the actual
resource boundaries are not of interest (e.g., it might be relevant for
DIMMs, exposed via /proc/iomem to user space). We really want to merge
added resources in this scenario where possible.

Resources are effectively stored in a list-based tree. Having a lot of
resources not only wastes memory, it also makes traversing that tree more
expensive, and makes /proc/iomem explode in size (e.g., requiring
kexec-tools to manually merge resources when creating a kdump header. The
current kexec-tools resource count limit does not allow for more than
~100GB of memory with a memory block size of 128MB on x86-64).

Let's allow to selectively merge system ram resources by specifying a
new flag for add_memory*(). Patch #5 contains a /proc/iomem example. Only
tested with virtio-mem.

v2 -> v3:
- "mm/memory_hotplug: prepare passing flags to add_memory() and friends"
-- Use proper __bitwise type for flags
-- Use "MHP_NONE" for empty flags
- Rebased to latest -next, added rb's

v1 -> v2:
- I had another look at v1 after vacation and didn't like it - it felt like
  a hack. So I want forward and added a proper flag to add_memory*(), and
  introduce a clean (non-racy) way to mark System RAM resources mergeable.
- "kernel/resource: move and rename IORESOURCE_MEM_DRIVER_MANAGED"
-- Clean that flag up, felt wrong in the PnP section
- "mm/memory_hotplug: prepare passing flags to add_memory() and friends"
-- Previously sent in other context - decided to keep Wei's ack
- "mm/memory_hotplug: MEMHP_MERGE_RESOURCE to specify merging of System
   RAM resources"
-- Cleaner approach to get the job done by using proper flags and only
   merging the single, specified resource
- "virtio-mem: try to merge system ram resources"
  "xen/balloon: try to merge system ram resources"
  "hv_balloon: try to merge system ram resources"
-- Use the new flag MEMHP_MERGE_RESOURCE, much cleaner

RFC -> v1:
- Switch from rather generic "merge_child_mem_resources()" where a resource
  name has to be specified to "merge_system_ram_resources().
- Smaller comment/documentation/patch description changes/fixes

David Hildenbrand (7):
  kernel/resource: make release_mem_region_adjustable() never fail
  kernel/resource: move and rename IORESOURCE_MEM_DRIVER_MANAGED
  mm/memory_hotplug: prepare passing flags to add_memory() and friends
  mm/memory_hotplug: MEMHP_MERGE_RESOURCE to specify merging of System
    RAM resources
  virtio-mem: try to merge system ram resources
  xen/balloon: try to merge system ram resources
  hv_balloon: try to merge system ram resources

 arch/powerpc/platforms/powernv/memtrace.c     |   2 +-
 .../platforms/pseries/hotplug-memory.c        |   2 +-
 drivers/acpi/acpi_memhotplug.c                |   3 +-
 drivers/base/memory.c                         |   3 +-
 drivers/dax/kmem.c                            |   2 +-
 drivers/hv/hv_balloon.c                       |   2 +-
 drivers/s390/char/sclp_cmd.c                  |   2 +-
 drivers/virtio/virtio_mem.c                   |   3 +-
 drivers/xen/balloon.c                         |   2 +-
 include/linux/ioport.h                        |  12 +-
 include/linux/memory_hotplug.h                |  23 +++-
 kernel/kexec_file.c                           |   2 +-
 kernel/resource.c                             | 109 ++++++++++++++----
 mm/memory_hotplug.c                           |  47 +++-----
 14 files changed, 146 insertions(+), 68 deletions(-)

-- 
2.26.2
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^ permalink raw reply	[flat|nested] 14+ messages in thread

end of thread, other threads:[~2020-09-15  8:34 UTC | newest]

Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-09-10  9:13 [PATCH v3 0/7] mm/memory_hotplug: selective merging of system ram resources David Hildenbrand
2020-09-10  9:13 ` [PATCH v3 1/7] kernel/resource: make release_mem_region_adjustable() never fail David Hildenbrand
2020-09-10  9:13 ` [PATCH v3 2/7] kernel/resource: move and rename IORESOURCE_MEM_DRIVER_MANAGED David Hildenbrand
2020-09-10  9:13 ` [PATCH v3 3/7] mm/memory_hotplug: prepare passing flags to add_memory() and friends David Hildenbrand
2020-09-10  9:53   ` Pankaj Gupta
2020-09-11  2:21   ` kernel test robot
2020-09-11  8:20     ` David Hildenbrand
2020-09-15  8:46   ` kernel test robot
2020-09-10  9:13 ` [PATCH v3 4/7] mm/memory_hotplug: MEMHP_MERGE_RESOURCE to specify merging of System RAM resources David Hildenbrand
2020-09-10 10:03   ` Pankaj Gupta
2020-09-10  9:13 ` [PATCH v3 5/7] virtio-mem: try to merge system ram resources David Hildenbrand
2020-09-10 10:10   ` Pankaj Gupta
2020-09-10  9:13 ` [PATCH v3 6/7] xen/balloon: " David Hildenbrand
2020-09-10  9:13 ` [PATCH v3 7/7] hv_balloon: " David Hildenbrand

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