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| author |   Oscar Salvador <osalvador@suse.de> | 2021-05-04 18:39:48 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2021-05-05 11:27:27 -0700 |
| commit | e3a9d9fcc3315993de2e9fcd7ea82fab84433815 (patch) | |
| tree | 0ae5712c9f1a5b34f8f485bf05887e983b652d1c /Documentation | |
| parent | acpi,memhotplug: enable MHP_MEMMAP_ON_MEMORY when supported (diff) | |
| download | linux-dev-e3a9d9fcc3315993de2e9fcd7ea82fab84433815.tar.xz linux-dev-e3a9d9fcc3315993de2e9fcd7ea82fab84433815.zip | |
mm,memory_hotplug: add kernel boot option to enable memmap_on_memory
Self stored memmap leads to a sparse memory situation which is
unsuitable for workloads that requires large contiguous memory chunks,
so make this an opt-in which needs to be explicitly enabled.
To control this, let memory_hotplug have its own memory space, as
suggested by David, so we can add memory_hotplug.memmap_on_memory
parameter.
Link: https://lkml.kernel.org/r/20210421102701.25051-7-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 1c0a3cf6fcc9..d93fbc1c1917 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2801,6 +2801,23 @@ seconds. Use this parameter to check at some other rate. 0 disables periodic checking. + memory_hotplug.memmap_on_memory + [KNL,X86,ARM] Boolean flag to enable this feature. + Format: {on | off (default)} + When enabled, runtime hotplugged memory will + allocate its internal metadata (struct pages) + from the hotadded memory which will allow to + hotadd a lot of memory without requiring + additional memory to do so. + This feature is disabled by default because it + has some implication on large (e.g. GB) + allocations in some configurations (e.g. small + memory blocks). + The state of the flag can be read in + /sys/module/memory_hotplug/parameters/memmap_on_memory. + Note that even when enabled, there are a few cases where + the feature is not effective. + memtest= [KNL,X86,ARM,PPC] Enable memtest Format: <integer> default : 0 <disable> |