Lines Matching +full:in +full:- +full:memory
1 # SPDX-License-Identifier: GPL-2.0-only
3 menu "Memory Management options"
10 prompt "Memory model"
17 Linux manages its memory internally. Most users will
22 bool "Flat Memory"
25 This option is best suited for non-NUMA systems with
27 system in terms of performance and resource consumption
30 For systems that have holes in their physical address
31 spaces and for features like NUMA and memory hotplug,
32 choose "Sparse Memory".
34 If unsure, choose this option (Flat Memory) over any other.
37 bool "Discontiguous Memory"
41 memory systems, over FLATMEM. These systems have holes
42 in their physical address spaces, and this option provides
45 Although "Discontiguous Memory" is still used by several
46 architectures, it is considered deprecated in favor of
47 "Sparse Memory".
49 If unsure, choose "Sparse Memory" over this option.
52 bool "Sparse Memory"
56 memory hot-plug systems. This is normal.
59 holes is their physical address space and allows memory
60 hot-plug and hot-remove.
62 If unsure, choose "Flat Memory" over this option.
84 # to represent different areas of memory. This variable allows
105 # Architecture platforms which require a two level mem_section in SPARSEMEM
117 bool "Sparse Memory virtual memmap"
132 # Don't discard allocated memory used to track "memory" and "reserved" memblocks
133 # after early boot, so it can still be used to test for validity of memory.
134 # Also, memblocks are updated with memory hot(un)plug.
138 # Keep arch NUMA mapping infrastructure post-init.
146 # Only be set on architectures that have completely implemented memory hotplug
154 bool "Allow for memory hot-add"
166 bool "Online the newly added memory blocks by default"
169 This option sets the default policy setting for memory hotplug
170 onlining policy (/sys/devices/system/memory/auto_online_blocks) which
171 determines what happens to newly added memory regions. Policy setting
173 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
175 Say Y here if you want all hot-plugged memory blocks to appear in
177 Say N here if you want the default policy to keep all hot-plugged
178 memory blocks in 'offline' state.
181 bool "Allow for memory hot remove"
186 # Heavily threaded applications may benefit from splitting the mm-wide
190 # ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
191 # PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
193 # a per-page lock leads to problems when multiple tables need to be locked
209 # support for memory balloon
214 # support for memory balloon compaction
216 bool "Allow for balloon memory compaction/migration"
220 Memory fragmentation introduced by ballooning might reduce
221 significantly the number of 2MB contiguous memory blocks that can be
224 by the guest workload. Allowing the compaction & migration for memory
225 pages enlisted as being part of memory balloon devices avoids the
226 scenario aforementioned and helps improving memory defragmentation.
229 # support for memory compaction
231 bool "Allow for memory compaction"
236 Compaction is the only memory management component to form
237 high order (larger physically contiguous) memory blocks
240 invocations for high order memory requests. You shouldn't
243 linux-mm@kvack.org.
254 memory can be freed within the host for other uses.
265 while the virtual addresses are not changed. This is useful in
289 the full range of memory available to the CPU. Enabled
315 saving memory until one or another app needs to modify the content.
326 This is the portion of low virtual memory which should be protected
346 bool "Enable recovery from hardware memory errors"
350 Enables code to recover from some memory failures on systems
352 even when some of its memory has uncorrected errors. This requires
353 special hardware support and typically ECC memory.
366 of memory on which to store mappings, but it can only ask the system
367 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
376 long-term mappings means that the space is wasted.
386 See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
397 applications by speeding up page faults during memory
401 If memory constrained on embedded, you may want to say N.
414 memory footprint of applications without a guaranteed
423 memory footprint of applications without a guaranteed
434 Swap transparent huge pages in one piece, without splitting.
451 Cleancache can be thought of as a page-granularity victim cache
454 memory. So when the PFRA "evicts" a page, it first attempts to use
455 cleancache code to put the data contained in that page into
456 "transcendent memory", memory that is not directly accessible or
458 time-varying size. And when a cleancache-enabled
459 filesystem wishes to access a page in a file on disk, it first
462 When a transcendent memory driver is available (such as zcache or
463 Xen transcendent memory), a significant I/O reduction
465 are reduced to a single pointer-compare-against-NULL resulting
466 in a negligible performance hit.
476 "transcendent memory", memory that is not directly accessible or
478 time-varying size. When space in transcendent memory is available,
480 available, all frontswap calls are reduced to a single pointer-
481 compare-against-NULL resulting in a negligible performance hit
487 bool "Contiguous Memory Allocator"
492 This enables the Contiguous Memory Allocator which allows other
493 subsystems to allocate big physically-contiguous blocks of memory.
494 CMA reserves a region of memory and allows only movable pages to
495 be allocated from it. This way, the kernel can use the memory for
505 This forbids the CMA to active its pages to system memory, to keep
514 Turns on debug messages in CMA. This produces KERN_DEBUG
529 Turns on the bitmap_hex node under DEBUGFS, shows the bitmap in hex
547 number of CMA area in the system.
549 If unsure, leave the default value "7" in UMA and "19" in NUMA.
552 bool "Track memory changes"
556 This option enables memory changes tracking by introducing a
557 soft-dirty bit on pte-s. This bit it set when someone writes
561 See Documentation/admin-guide/mm/soft-dirty.rst for more details.
569 pages that are in the process of being swapped out and attempts to
570 compress them into a dynamically allocated RAM-based memory pool.
571 This can result in a significant I/O reduction on swap device and,
572 in the case where decompressing from RAM is faster that swap device
576 v3.11) that interacts heavily with memory reclaim. While these
577 interactions don't cause any known issues on simple memory setups,
594 If in doubt, select 'LZO'.
699 tristate "Common API for compressed memory storage"
701 Compressed memory storage API. This allows using either zbud or
723 tristate "Memory allocator for compressed pages"
726 zsmalloc is a slab-based memory allocator designed to store
727 compressed RAM pages. zsmalloc uses virtual memory mapping
728 in order to reduce fragmentation. However, this results in a
729 non-standard allocator interface where a handle, not a pointer, is
730 returned by an alloc(). This handle must be mapped in order to
738 This option enables code in the zsmalloc to collect various
739 statistics about whats happening in zsmalloc and exports that
747 int "Maximum user stack size for 32-bit processes (MB)"
752 This is the maximum stack size in Megabytes in the VM layout of 32-bit
754 arch). The stack will be located at the highest memory address minus
756 smaller value in which case that is used.
767 Ordinarily all struct pages are initialised during early boot in a
770 a subset of memmap at boot and then initialise the rest in parallel.
771 This has a potential performance impact on tasks running early in the
780 bit writers can set the state of the bit in the flags so that PTE
790 be useful to tune memory cgroup limits and/or for job placement
793 See Documentation/admin-guide/mm/idle_page_tracking.rst for
800 bool "Device memory (pmem, HMM, etc...) hotplug support"
808 Device memory hotplug support allows for establishing pmem,
809 or other device driver discovered memory regions, in the
811 "device-physical" addresses which is needed for using a DAX
812 mapping in an O_DIRECT operation, among other things.
828 bool "Unaddressable device memory (GPU memory, ...)"
834 memory; i.e., memory that is only accessible from the device (or
849 bool "Collect percpu memory statistics"
853 be used to help understand percpu memory usage.
867 since the page fault handler will not wait for other threads memory
868 layout change to be done, assuming that this change is done in another
869 part of the process's memory space. This type of page fault is named
889 bool "Read-only THP for filesystems (EXPERIMENTAL)"
893 Allow khugepaged to put read-only file-backed pages in THP.
896 support of file THPs will be developed in the next few release