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899 lines
28 KiB
899 lines
28 KiB
# SPDX-License-Identifier: GPL-2.0-only |
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menu "Memory Management options" |
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config SELECT_MEMORY_MODEL |
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def_bool y |
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depends on ARCH_SELECT_MEMORY_MODEL |
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choice |
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prompt "Memory model" |
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depends on SELECT_MEMORY_MODEL |
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default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT |
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default FLATMEM_MANUAL |
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help |
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This option allows you to change some of the ways that |
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Linux manages its memory internally. Most users will |
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only have one option here selected by the architecture |
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configuration. This is normal. |
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config FLATMEM_MANUAL |
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bool "Flat Memory" |
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depends on !ARCH_SPARSEMEM_ENABLE || ARCH_FLATMEM_ENABLE |
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help |
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This option is best suited for non-NUMA systems with |
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flat address space. The FLATMEM is the most efficient |
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system in terms of performance and resource consumption |
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and it is the best option for smaller systems. |
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For systems that have holes in their physical address |
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spaces and for features like NUMA and memory hotplug, |
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choose "Sparse Memory". |
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If unsure, choose this option (Flat Memory) over any other. |
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config SPARSEMEM_MANUAL |
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bool "Sparse Memory" |
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depends on ARCH_SPARSEMEM_ENABLE |
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help |
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This will be the only option for some systems, including |
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memory hot-plug systems. This is normal. |
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This option provides efficient support for systems with |
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holes is their physical address space and allows memory |
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hot-plug and hot-remove. |
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If unsure, choose "Flat Memory" over this option. |
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endchoice |
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config SPARSEMEM |
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def_bool y |
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depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL |
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config FLATMEM |
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def_bool y |
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depends on !SPARSEMEM || FLATMEM_MANUAL |
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# |
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# SPARSEMEM_EXTREME (which is the default) does some bootmem |
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# allocations when sparse_init() is called. If this cannot |
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# be done on your architecture, select this option. However, |
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# statically allocating the mem_section[] array can potentially |
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# consume vast quantities of .bss, so be careful. |
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# |
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# This option will also potentially produce smaller runtime code |
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# with gcc 3.4 and later. |
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# |
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config SPARSEMEM_STATIC |
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bool |
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# |
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# Architecture platforms which require a two level mem_section in SPARSEMEM |
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# must select this option. This is usually for architecture platforms with |
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# an extremely sparse physical address space. |
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# |
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config SPARSEMEM_EXTREME |
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def_bool y |
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depends on SPARSEMEM && !SPARSEMEM_STATIC |
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config SPARSEMEM_VMEMMAP_ENABLE |
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bool |
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config SPARSEMEM_VMEMMAP |
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bool "Sparse Memory virtual memmap" |
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depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE |
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default y |
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help |
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SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise |
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pfn_to_page and page_to_pfn operations. This is the most |
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efficient option when sufficient kernel resources are available. |
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config HAVE_MEMBLOCK_PHYS_MAP |
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bool |
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config HAVE_FAST_GUP |
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depends on MMU |
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bool |
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# Don't discard allocated memory used to track "memory" and "reserved" memblocks |
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# after early boot, so it can still be used to test for validity of memory. |
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# Also, memblocks are updated with memory hot(un)plug. |
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config ARCH_KEEP_MEMBLOCK |
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bool |
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# Keep arch NUMA mapping infrastructure post-init. |
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config NUMA_KEEP_MEMINFO |
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bool |
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config MEMORY_ISOLATION |
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bool |
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# |
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# Only be set on architectures that have completely implemented memory hotplug |
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# feature. If you are not sure, don't touch it. |
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# |
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config HAVE_BOOTMEM_INFO_NODE |
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def_bool n |
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config ARCH_ENABLE_MEMORY_HOTPLUG |
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bool |
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# eventually, we can have this option just 'select SPARSEMEM' |
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config MEMORY_HOTPLUG |
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bool "Allow for memory hot-add" |
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select MEMORY_ISOLATION |
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depends on SPARSEMEM || X86_64_ACPI_NUMA |
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depends on ARCH_ENABLE_MEMORY_HOTPLUG |
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depends on 64BIT || BROKEN |
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select NUMA_KEEP_MEMINFO if NUMA |
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config MEMORY_HOTPLUG_SPARSE |
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def_bool y |
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depends on SPARSEMEM && MEMORY_HOTPLUG |
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config MEMORY_HOTPLUG_DEFAULT_ONLINE |
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bool "Online the newly added memory blocks by default" |
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depends on MEMORY_HOTPLUG |
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help |
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This option sets the default policy setting for memory hotplug |
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onlining policy (/sys/devices/system/memory/auto_online_blocks) which |
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determines what happens to newly added memory regions. Policy setting |
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can always be changed at runtime. |
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See Documentation/admin-guide/mm/memory-hotplug.rst for more information. |
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Say Y here if you want all hot-plugged memory blocks to appear in |
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'online' state by default. |
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Say N here if you want the default policy to keep all hot-plugged |
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memory blocks in 'offline' state. |
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config ARCH_ENABLE_MEMORY_HOTREMOVE |
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bool |
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config MEMORY_HOTREMOVE |
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bool "Allow for memory hot remove" |
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select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64) |
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depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE |
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depends on MIGRATION |
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config MHP_MEMMAP_ON_MEMORY |
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def_bool y |
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depends on MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP |
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depends on ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE |
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# Heavily threaded applications may benefit from splitting the mm-wide |
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# page_table_lock, so that faults on different parts of the user address |
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# space can be handled with less contention: split it at this NR_CPUS. |
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# Default to 4 for wider testing, though 8 might be more appropriate. |
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# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock. |
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# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes. |
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# SPARC32 allocates multiple pte tables within a single page, and therefore |
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# a per-page lock leads to problems when multiple tables need to be locked |
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# at the same time (e.g. copy_page_range()). |
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# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page. |
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# |
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config SPLIT_PTLOCK_CPUS |
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int |
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default "999999" if !MMU |
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default "999999" if ARM && !CPU_CACHE_VIPT |
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default "999999" if PARISC && !PA20 |
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default "999999" if SPARC32 |
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default "4" |
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config ARCH_ENABLE_SPLIT_PMD_PTLOCK |
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bool |
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# |
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# support for memory balloon |
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config MEMORY_BALLOON |
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bool |
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# |
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# support for memory balloon compaction |
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config BALLOON_COMPACTION |
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bool "Allow for balloon memory compaction/migration" |
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def_bool y |
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depends on COMPACTION && MEMORY_BALLOON |
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help |
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Memory fragmentation introduced by ballooning might reduce |
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significantly the number of 2MB contiguous memory blocks that can be |
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used within a guest, thus imposing performance penalties associated |
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with the reduced number of transparent huge pages that could be used |
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by the guest workload. Allowing the compaction & migration for memory |
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pages enlisted as being part of memory balloon devices avoids the |
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scenario aforementioned and helps improving memory defragmentation. |
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# |
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# support for memory compaction |
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config COMPACTION |
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bool "Allow for memory compaction" |
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def_bool y |
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select MIGRATION |
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depends on MMU |
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help |
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Compaction is the only memory management component to form |
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high order (larger physically contiguous) memory blocks |
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reliably. The page allocator relies on compaction heavily and |
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the lack of the feature can lead to unexpected OOM killer |
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invocations for high order memory requests. You shouldn't |
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disable this option unless there really is a strong reason for |
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it and then we would be really interested to hear about that at |
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[email protected]. |
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# |
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# support for free page reporting |
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config PAGE_REPORTING |
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bool "Free page reporting" |
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def_bool n |
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help |
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Free page reporting allows for the incremental acquisition of |
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free pages from the buddy allocator for the purpose of reporting |
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those pages to another entity, such as a hypervisor, so that the |
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memory can be freed within the host for other uses. |
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# |
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# support for page migration |
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# |
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config MIGRATION |
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bool "Page migration" |
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def_bool y |
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depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU |
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help |
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Allows the migration of the physical location of pages of processes |
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while the virtual addresses are not changed. This is useful in |
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two situations. The first is on NUMA systems to put pages nearer |
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to the processors accessing. The second is when allocating huge |
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pages as migration can relocate pages to satisfy a huge page |
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allocation instead of reclaiming. |
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config ARCH_ENABLE_HUGEPAGE_MIGRATION |
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bool |
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config ARCH_ENABLE_THP_MIGRATION |
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bool |
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config HUGETLB_PAGE_SIZE_VARIABLE |
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def_bool n |
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help |
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Allows the pageblock_order value to be dynamic instead of just standard |
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HUGETLB_PAGE_ORDER when there are multiple HugeTLB page sizes available |
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on a platform. |
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config CONTIG_ALLOC |
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def_bool (MEMORY_ISOLATION && COMPACTION) || CMA |
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config PHYS_ADDR_T_64BIT |
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def_bool 64BIT |
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config BOUNCE |
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bool "Enable bounce buffers" |
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default y |
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depends on BLOCK && MMU && HIGHMEM |
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help |
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Enable bounce buffers for devices that cannot access the full range of |
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memory available to the CPU. Enabled by default when HIGHMEM is |
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selected, but you may say n to override this. |
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config VIRT_TO_BUS |
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bool |
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help |
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An architecture should select this if it implements the |
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deprecated interface virt_to_bus(). All new architectures |
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should probably not select this. |
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config MMU_NOTIFIER |
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bool |
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select SRCU |
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select INTERVAL_TREE |
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config KSM |
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bool "Enable KSM for page merging" |
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depends on MMU |
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select XXHASH |
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help |
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Enable Kernel Samepage Merging: KSM periodically scans those areas |
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of an application's address space that an app has advised may be |
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mergeable. When it finds pages of identical content, it replaces |
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the many instances by a single page with that content, so |
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saving memory until one or another app needs to modify the content. |
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Recommended for use with KVM, or with other duplicative applications. |
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See Documentation/vm/ksm.rst for more information: KSM is inactive |
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until a program has madvised that an area is MADV_MERGEABLE, and |
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root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set). |
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config DEFAULT_MMAP_MIN_ADDR |
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int "Low address space to protect from user allocation" |
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depends on MMU |
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default 4096 |
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help |
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This is the portion of low virtual memory which should be protected |
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from userspace allocation. Keeping a user from writing to low pages |
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can help reduce the impact of kernel NULL pointer bugs. |
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For most ia64, ppc64 and x86 users with lots of address space |
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a value of 65536 is reasonable and should cause no problems. |
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On arm and other archs it should not be higher than 32768. |
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Programs which use vm86 functionality or have some need to map |
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this low address space will need CAP_SYS_RAWIO or disable this |
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protection by setting the value to 0. |
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This value can be changed after boot using the |
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/proc/sys/vm/mmap_min_addr tunable. |
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config ARCH_SUPPORTS_MEMORY_FAILURE |
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bool |
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config MEMORY_FAILURE |
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depends on MMU |
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depends on ARCH_SUPPORTS_MEMORY_FAILURE |
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bool "Enable recovery from hardware memory errors" |
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select MEMORY_ISOLATION |
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select RAS |
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help |
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Enables code to recover from some memory failures on systems |
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with MCA recovery. This allows a system to continue running |
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even when some of its memory has uncorrected errors. This requires |
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special hardware support and typically ECC memory. |
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config HWPOISON_INJECT |
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tristate "HWPoison pages injector" |
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depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS |
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select PROC_PAGE_MONITOR |
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config NOMMU_INITIAL_TRIM_EXCESS |
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int "Turn on mmap() excess space trimming before booting" |
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depends on !MMU |
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default 1 |
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help |
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The NOMMU mmap() frequently needs to allocate large contiguous chunks |
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of memory on which to store mappings, but it can only ask the system |
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allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently |
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more than it requires. To deal with this, mmap() is able to trim off |
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the excess and return it to the allocator. |
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If trimming is enabled, the excess is trimmed off and returned to the |
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system allocator, which can cause extra fragmentation, particularly |
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if there are a lot of transient processes. |
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If trimming is disabled, the excess is kept, but not used, which for |
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long-term mappings means that the space is wasted. |
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Trimming can be dynamically controlled through a sysctl option |
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(/proc/sys/vm/nr_trim_pages) which specifies the minimum number of |
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excess pages there must be before trimming should occur, or zero if |
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no trimming is to occur. |
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This option specifies the initial value of this option. The default |
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of 1 says that all excess pages should be trimmed. |
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See Documentation/admin-guide/mm/nommu-mmap.rst for more information. |
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config TRANSPARENT_HUGEPAGE |
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bool "Transparent Hugepage Support" |
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depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE |
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select COMPACTION |
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select XARRAY_MULTI |
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help |
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Transparent Hugepages allows the kernel to use huge pages and |
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huge tlb transparently to the applications whenever possible. |
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This feature can improve computing performance to certain |
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applications by speeding up page faults during memory |
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allocation, by reducing the number of tlb misses and by speeding |
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up the pagetable walking. |
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If memory constrained on embedded, you may want to say N. |
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choice |
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prompt "Transparent Hugepage Support sysfs defaults" |
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depends on TRANSPARENT_HUGEPAGE |
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default TRANSPARENT_HUGEPAGE_ALWAYS |
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help |
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Selects the sysfs defaults for Transparent Hugepage Support. |
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config TRANSPARENT_HUGEPAGE_ALWAYS |
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bool "always" |
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help |
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Enabling Transparent Hugepage always, can increase the |
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memory footprint of applications without a guaranteed |
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benefit but it will work automatically for all applications. |
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config TRANSPARENT_HUGEPAGE_MADVISE |
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bool "madvise" |
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help |
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Enabling Transparent Hugepage madvise, will only provide a |
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performance improvement benefit to the applications using |
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madvise(MADV_HUGEPAGE) but it won't risk to increase the |
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memory footprint of applications without a guaranteed |
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benefit. |
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endchoice |
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config ARCH_WANTS_THP_SWAP |
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def_bool n |
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config THP_SWAP |
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def_bool y |
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depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP && SWAP |
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help |
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Swap transparent huge pages in one piece, without splitting. |
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XXX: For now, swap cluster backing transparent huge page |
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will be split after swapout. |
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For selection by architectures with reasonable THP sizes. |
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# |
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# UP and nommu archs use km based percpu allocator |
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# |
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config NEED_PER_CPU_KM |
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depends on !SMP |
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bool |
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default y |
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config CLEANCACHE |
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bool "Enable cleancache driver to cache clean pages if tmem is present" |
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help |
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Cleancache can be thought of as a page-granularity victim cache |
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for clean pages that the kernel's pageframe replacement algorithm |
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(PFRA) would like to keep around, but can't since there isn't enough |
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memory. So when the PFRA "evicts" a page, it first attempts to use |
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cleancache code to put the data contained in that page into |
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"transcendent memory", memory that is not directly accessible or |
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addressable by the kernel and is of unknown and possibly |
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time-varying size. And when a cleancache-enabled |
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filesystem wishes to access a page in a file on disk, it first |
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checks cleancache to see if it already contains it; if it does, |
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the page is copied into the kernel and a disk access is avoided. |
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When a transcendent memory driver is available (such as zcache or |
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Xen transcendent memory), a significant I/O reduction |
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may be achieved. When none is available, all cleancache calls |
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are reduced to a single pointer-compare-against-NULL resulting |
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in a negligible performance hit. |
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If unsure, say Y to enable cleancache |
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config FRONTSWAP |
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bool "Enable frontswap to cache swap pages if tmem is present" |
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depends on SWAP |
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help |
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Frontswap is so named because it can be thought of as the opposite |
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of a "backing" store for a swap device. The data is stored into |
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"transcendent memory", memory that is not directly accessible or |
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addressable by the kernel and is of unknown and possibly |
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time-varying size. When space in transcendent memory is available, |
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a significant swap I/O reduction may be achieved. When none is |
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available, all frontswap calls are reduced to a single pointer- |
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compare-against-NULL resulting in a negligible performance hit |
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and swap data is stored as normal on the matching swap device. |
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If unsure, say Y to enable frontswap. |
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config CMA |
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bool "Contiguous Memory Allocator" |
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depends on MMU |
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select MIGRATION |
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select MEMORY_ISOLATION |
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help |
|
This enables the Contiguous Memory Allocator which allows other |
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subsystems to allocate big physically-contiguous blocks of memory. |
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CMA reserves a region of memory and allows only movable pages to |
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be allocated from it. This way, the kernel can use the memory for |
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pagecache and when a subsystem requests for contiguous area, the |
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allocated pages are migrated away to serve the contiguous request. |
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If unsure, say "n". |
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|
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config CMA_DEBUG |
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bool "CMA debug messages (DEVELOPMENT)" |
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depends on DEBUG_KERNEL && CMA |
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help |
|
Turns on debug messages in CMA. This produces KERN_DEBUG |
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messages for every CMA call as well as various messages while |
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processing calls such as dma_alloc_from_contiguous(). |
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This option does not affect warning and error messages. |
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|
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config CMA_DEBUGFS |
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bool "CMA debugfs interface" |
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depends on CMA && DEBUG_FS |
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help |
|
Turns on the DebugFS interface for CMA. |
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|
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config CMA_SYSFS |
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bool "CMA information through sysfs interface" |
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depends on CMA && SYSFS |
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help |
|
This option exposes some sysfs attributes to get information |
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from CMA. |
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|
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config CMA_AREAS |
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int "Maximum count of the CMA areas" |
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depends on CMA |
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default 19 if NUMA |
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default 7 |
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help |
|
CMA allows to create CMA areas for particular purpose, mainly, |
|
used as device private area. This parameter sets the maximum |
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number of CMA area in the system. |
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|
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If unsure, leave the default value "7" in UMA and "19" in NUMA. |
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config MEM_SOFT_DIRTY |
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bool "Track memory changes" |
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depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS |
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select PROC_PAGE_MONITOR |
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help |
|
This option enables memory changes tracking by introducing a |
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soft-dirty bit on pte-s. This bit it set when someone writes |
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into a page just as regular dirty bit, but unlike the latter |
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it can be cleared by hands. |
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|
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See Documentation/admin-guide/mm/soft-dirty.rst for more details. |
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config ZSWAP |
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bool "Compressed cache for swap pages (EXPERIMENTAL)" |
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depends on FRONTSWAP && CRYPTO=y |
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select ZPOOL |
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help |
|
A lightweight compressed cache for swap pages. It takes |
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pages that are in the process of being swapped out and attempts to |
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compress them into a dynamically allocated RAM-based memory pool. |
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This can result in a significant I/O reduction on swap device and, |
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in the case where decompressing from RAM is faster that swap device |
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reads, can also improve workload performance. |
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|
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This is marked experimental because it is a new feature (as of |
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v3.11) that interacts heavily with memory reclaim. While these |
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interactions don't cause any known issues on simple memory setups, |
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they have not be fully explored on the large set of potential |
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configurations and workloads that exist. |
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|
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choice |
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prompt "Compressed cache for swap pages default compressor" |
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depends on ZSWAP |
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default ZSWAP_COMPRESSOR_DEFAULT_LZO |
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help |
|
Selects the default compression algorithm for the compressed cache |
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for swap pages. |
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|
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For an overview what kind of performance can be expected from |
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a particular compression algorithm please refer to the benchmarks |
|
available at the following LWN page: |
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https://lwn.net/Articles/751795/ |
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If in doubt, select 'LZO'. |
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|
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The selection made here can be overridden by using the kernel |
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command line 'zswap.compressor=' option. |
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|
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config ZSWAP_COMPRESSOR_DEFAULT_DEFLATE |
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bool "Deflate" |
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select CRYPTO_DEFLATE |
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help |
|
Use the Deflate algorithm as the default compression algorithm. |
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|
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config ZSWAP_COMPRESSOR_DEFAULT_LZO |
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bool "LZO" |
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select CRYPTO_LZO |
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help |
|
Use the LZO algorithm as the default compression algorithm. |
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|
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config ZSWAP_COMPRESSOR_DEFAULT_842 |
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bool "842" |
|
select CRYPTO_842 |
|
help |
|
Use the 842 algorithm as the default compression algorithm. |
|
|
|
config ZSWAP_COMPRESSOR_DEFAULT_LZ4 |
|
bool "LZ4" |
|
select CRYPTO_LZ4 |
|
help |
|
Use the LZ4 algorithm as the default compression algorithm. |
|
|
|
config ZSWAP_COMPRESSOR_DEFAULT_LZ4HC |
|
bool "LZ4HC" |
|
select CRYPTO_LZ4HC |
|
help |
|
Use the LZ4HC algorithm as the default compression algorithm. |
|
|
|
config ZSWAP_COMPRESSOR_DEFAULT_ZSTD |
|
bool "zstd" |
|
select CRYPTO_ZSTD |
|
help |
|
Use the zstd algorithm as the default compression algorithm. |
|
endchoice |
|
|
|
config ZSWAP_COMPRESSOR_DEFAULT |
|
string |
|
depends on ZSWAP |
|
default "deflate" if ZSWAP_COMPRESSOR_DEFAULT_DEFLATE |
|
default "lzo" if ZSWAP_COMPRESSOR_DEFAULT_LZO |
|
default "842" if ZSWAP_COMPRESSOR_DEFAULT_842 |
|
default "lz4" if ZSWAP_COMPRESSOR_DEFAULT_LZ4 |
|
default "lz4hc" if ZSWAP_COMPRESSOR_DEFAULT_LZ4HC |
|
default "zstd" if ZSWAP_COMPRESSOR_DEFAULT_ZSTD |
|
default "" |
|
|
|
choice |
|
prompt "Compressed cache for swap pages default allocator" |
|
depends on ZSWAP |
|
default ZSWAP_ZPOOL_DEFAULT_ZBUD |
|
help |
|
Selects the default allocator for the compressed cache for |
|
swap pages. |
|
The default is 'zbud' for compatibility, however please do |
|
read the description of each of the allocators below before |
|
making a right choice. |
|
|
|
The selection made here can be overridden by using the kernel |
|
command line 'zswap.zpool=' option. |
|
|
|
config ZSWAP_ZPOOL_DEFAULT_ZBUD |
|
bool "zbud" |
|
select ZBUD |
|
help |
|
Use the zbud allocator as the default allocator. |
|
|
|
config ZSWAP_ZPOOL_DEFAULT_Z3FOLD |
|
bool "z3fold" |
|
select Z3FOLD |
|
help |
|
Use the z3fold allocator as the default allocator. |
|
|
|
config ZSWAP_ZPOOL_DEFAULT_ZSMALLOC |
|
bool "zsmalloc" |
|
select ZSMALLOC |
|
help |
|
Use the zsmalloc allocator as the default allocator. |
|
endchoice |
|
|
|
config ZSWAP_ZPOOL_DEFAULT |
|
string |
|
depends on ZSWAP |
|
default "zbud" if ZSWAP_ZPOOL_DEFAULT_ZBUD |
|
default "z3fold" if ZSWAP_ZPOOL_DEFAULT_Z3FOLD |
|
default "zsmalloc" if ZSWAP_ZPOOL_DEFAULT_ZSMALLOC |
|
default "" |
|
|
|
config ZSWAP_DEFAULT_ON |
|
bool "Enable the compressed cache for swap pages by default" |
|
depends on ZSWAP |
|
help |
|
If selected, the compressed cache for swap pages will be enabled |
|
at boot, otherwise it will be disabled. |
|
|
|
The selection made here can be overridden by using the kernel |
|
command line 'zswap.enabled=' option. |
|
|
|
config ZPOOL |
|
tristate "Common API for compressed memory storage" |
|
help |
|
Compressed memory storage API. This allows using either zbud or |
|
zsmalloc. |
|
|
|
config ZBUD |
|
tristate "Low (Up to 2x) density storage for compressed pages" |
|
depends on ZPOOL |
|
help |
|
A special purpose allocator for storing compressed pages. |
|
It is designed to store up to two compressed pages per physical |
|
page. While this design limits storage density, it has simple and |
|
deterministic reclaim properties that make it preferable to a higher |
|
density approach when reclaim will be used. |
|
|
|
config Z3FOLD |
|
tristate "Up to 3x density storage for compressed pages" |
|
depends on ZPOOL |
|
help |
|
A special purpose allocator for storing compressed pages. |
|
It is designed to store up to three compressed pages per physical |
|
page. It is a ZBUD derivative so the simplicity and determinism are |
|
still there. |
|
|
|
config ZSMALLOC |
|
tristate "Memory allocator for compressed pages" |
|
depends on MMU |
|
help |
|
zsmalloc is a slab-based memory allocator designed to store |
|
compressed RAM pages. zsmalloc uses virtual memory mapping |
|
in order to reduce fragmentation. However, this results in a |
|
non-standard allocator interface where a handle, not a pointer, is |
|
returned by an alloc(). This handle must be mapped in order to |
|
access the allocated space. |
|
|
|
config ZSMALLOC_STAT |
|
bool "Export zsmalloc statistics" |
|
depends on ZSMALLOC |
|
select DEBUG_FS |
|
help |
|
This option enables code in the zsmalloc to collect various |
|
statistics about what's happening in zsmalloc and exports that |
|
information to userspace via debugfs. |
|
If unsure, say N. |
|
|
|
config GENERIC_EARLY_IOREMAP |
|
bool |
|
|
|
config STACK_MAX_DEFAULT_SIZE_MB |
|
int "Default maximum user stack size for 32-bit processes (MB)" |
|
default 100 |
|
range 8 2048 |
|
depends on STACK_GROWSUP && (!64BIT || COMPAT) |
|
help |
|
This is the maximum stack size in Megabytes in the VM layout of 32-bit |
|
user processes when the stack grows upwards (currently only on parisc |
|
arch) when the RLIMIT_STACK hard limit is unlimited. |
|
|
|
A sane initial value is 100 MB. |
|
|
|
config DEFERRED_STRUCT_PAGE_INIT |
|
bool "Defer initialisation of struct pages to kthreads" |
|
depends on SPARSEMEM |
|
depends on !NEED_PER_CPU_KM |
|
depends on 64BIT |
|
select PADATA |
|
help |
|
Ordinarily all struct pages are initialised during early boot in a |
|
single thread. On very large machines this can take a considerable |
|
amount of time. If this option is set, large machines will bring up |
|
a subset of memmap at boot and then initialise the rest in parallel. |
|
This has a potential performance impact on tasks running early in the |
|
lifetime of the system until these kthreads finish the |
|
initialisation. |
|
|
|
config PAGE_IDLE_FLAG |
|
bool |
|
select PAGE_EXTENSION if !64BIT |
|
help |
|
This adds PG_idle and PG_young flags to 'struct page'. PTE Accessed |
|
bit writers can set the state of the bit in the flags so that PTE |
|
Accessed bit readers may avoid disturbance. |
|
|
|
config IDLE_PAGE_TRACKING |
|
bool "Enable idle page tracking" |
|
depends on SYSFS && MMU |
|
select PAGE_IDLE_FLAG |
|
help |
|
This feature allows to estimate the amount of user pages that have |
|
not been touched during a given period of time. This information can |
|
be useful to tune memory cgroup limits and/or for job placement |
|
within a compute cluster. |
|
|
|
See Documentation/admin-guide/mm/idle_page_tracking.rst for |
|
more details. |
|
|
|
config ARCH_HAS_CACHE_LINE_SIZE |
|
bool |
|
|
|
config ARCH_HAS_PTE_DEVMAP |
|
bool |
|
|
|
config ARCH_HAS_ZONE_DMA_SET |
|
bool |
|
|
|
config ZONE_DMA |
|
bool "Support DMA zone" if ARCH_HAS_ZONE_DMA_SET |
|
default y if ARM64 || X86 |
|
|
|
config ZONE_DMA32 |
|
bool "Support DMA32 zone" if ARCH_HAS_ZONE_DMA_SET |
|
depends on !X86_32 |
|
default y if ARM64 |
|
|
|
config ZONE_DEVICE |
|
bool "Device memory (pmem, HMM, etc...) hotplug support" |
|
depends on MEMORY_HOTPLUG |
|
depends on MEMORY_HOTREMOVE |
|
depends on SPARSEMEM_VMEMMAP |
|
depends on ARCH_HAS_PTE_DEVMAP |
|
select XARRAY_MULTI |
|
|
|
help |
|
Device memory hotplug support allows for establishing pmem, |
|
or other device driver discovered memory regions, in the |
|
memmap. This allows pfn_to_page() lookups of otherwise |
|
"device-physical" addresses which is needed for using a DAX |
|
mapping in an O_DIRECT operation, among other things. |
|
|
|
If FS_DAX is enabled, then say Y. |
|
|
|
config DEV_PAGEMAP_OPS |
|
bool |
|
|
|
# |
|
# Helpers to mirror range of the CPU page tables of a process into device page |
|
# tables. |
|
# |
|
config HMM_MIRROR |
|
bool |
|
depends on MMU |
|
|
|
config DEVICE_PRIVATE |
|
bool "Unaddressable device memory (GPU memory, ...)" |
|
depends on ZONE_DEVICE |
|
select DEV_PAGEMAP_OPS |
|
|
|
help |
|
Allows creation of struct pages to represent unaddressable device |
|
memory; i.e., memory that is only accessible from the device (or |
|
group of devices). You likely also want to select HMM_MIRROR. |
|
|
|
config VMAP_PFN |
|
bool |
|
|
|
config ARCH_USES_HIGH_VMA_FLAGS |
|
bool |
|
config ARCH_HAS_PKEYS |
|
bool |
|
|
|
config PERCPU_STATS |
|
bool "Collect percpu memory statistics" |
|
help |
|
This feature collects and exposes statistics via debugfs. The |
|
information includes global and per chunk statistics, which can |
|
be used to help understand percpu memory usage. |
|
|
|
config GUP_TEST |
|
bool "Enable infrastructure for get_user_pages()-related unit tests" |
|
depends on DEBUG_FS |
|
help |
|
Provides /sys/kernel/debug/gup_test, which in turn provides a way |
|
to make ioctl calls that can launch kernel-based unit tests for |
|
the get_user_pages*() and pin_user_pages*() family of API calls. |
|
|
|
These tests include benchmark testing of the _fast variants of |
|
get_user_pages*() and pin_user_pages*(), as well as smoke tests of |
|
the non-_fast variants. |
|
|
|
There is also a sub-test that allows running dump_page() on any |
|
of up to eight pages (selected by command line args) within the |
|
range of user-space addresses. These pages are either pinned via |
|
pin_user_pages*(), or pinned via get_user_pages*(), as specified |
|
by other command line arguments. |
|
|
|
See tools/testing/selftests/vm/gup_test.c |
|
|
|
comment "GUP_TEST needs to have DEBUG_FS enabled" |
|
depends on !GUP_TEST && !DEBUG_FS |
|
|
|
config GUP_GET_PTE_LOW_HIGH |
|
bool |
|
|
|
config READ_ONLY_THP_FOR_FS |
|
bool "Read-only THP for filesystems (EXPERIMENTAL)" |
|
depends on TRANSPARENT_HUGEPAGE && SHMEM |
|
|
|
help |
|
Allow khugepaged to put read-only file-backed pages in THP. |
|
|
|
This is marked experimental because it is a new feature. Write |
|
support of file THPs will be developed in the next few release |
|
cycles. |
|
|
|
config ARCH_HAS_PTE_SPECIAL |
|
bool |
|
|
|
# |
|
# Some architectures require a special hugepage directory format that is |
|
# required to support multiple hugepage sizes. For example a4fe3ce76 |
|
# "powerpc/mm: Allow more flexible layouts for hugepage pagetables" |
|
# introduced it on powerpc. This allows for a more flexible hugepage |
|
# pagetable layouts. |
|
# |
|
config ARCH_HAS_HUGEPD |
|
bool |
|
|
|
config MAPPING_DIRTY_HELPERS |
|
bool |
|
|
|
config KMAP_LOCAL |
|
bool |
|
|
|
# struct io_mapping based helper. Selected by drivers that need them |
|
config IO_MAPPING |
|
bool |
|
|
|
config SECRETMEM |
|
def_bool ARCH_HAS_SET_DIRECT_MAP && !EMBEDDED |
|
|
|
source "mm/damon/Kconfig" |
|
|
|
endmenu
|
|
|