| /linux/Documentation/admin-guide/mm/ |
| H A D | memory-hotplug.rst | 2 Memory Hot(Un)Plug
5 This document describes generic Linux support for memory hot(un)plug with
13 Memory hot(un)plug allows for increasing and decreasing the size of physical
14 memory available to a machine at runtime. In the simplest case, it consists of
18 Memory hot(un)plug is used for various purposes:
20 - The physical memory available to a machine can be adjusted at runtime, up- or
21 downgrading the memory capacity. This dynamic memory resizing, sometimes
26 example is replacing failing memory modules.
28 - Reducing energy consumption either by physically unplugging memory modules or
29 by logically unplugging (parts of) memory modules from Linux.
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| H A D | concepts.rst | 5 The memory management in Linux is a complex system that evolved over the
7 systems from MMU-less microcontrollers to supercomputers. The memory
16 Virtual Memory Primer
19 The physical memory in a computer system is a limited resource and
20 even for systems that support memory hotplug there is a hard limit on
21 the amount of memory that can be installed. The physical memory is not
27 All this makes dealing directly with physical memory quite complex and
28 to avoid this complexity a concept of virtual memory was developed.
30 The virtual memory abstracts the details of physical memory from the
32 physical memory (demand paging) and provides a mechanism for the
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| H A D | numaperf.rst | 2 NUMA Memory Performance
8 Some platforms may have multiple types of memory attached to a compute
9 node. These disparate memory ranges may share some characteristics, such
13 A system supports such heterogeneous memory by grouping each memory type
15 characteristics. Some memory may share the same node as a CPU, and others
16 are provided as memory only nodes. While memory only nodes do not provide
19 nodes with local memory and a memory only node for each of compute node::
30 A "memory initiator" is a node containing one or more devices such as
31 CPUs or separate memory I/O devices that can initiate memory requests.
32 A "memory target" is a node containing one or more physical address
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| /linux/tools/testing/selftests/memory-hotplug/ |
| H A D | mem-on-off-test.sh | 25 if ! ls $SYSFS/devices/system/memory/memory* > /dev/null 2>&1; then
26 echo $msg memory hotplug is not supported >&2
30 if ! grep -q 1 $SYSFS/devices/system/memory/memory*/removable; then
31 echo $msg no hot-pluggable memory >&2
37 # list all hot-pluggable memory
43 for memory in $SYSFS/devices/system/memory/memory*; do
44 if grep -q 1 $memory/removable &&
45 grep -q $state $memory/state; then
46 echo ${memory##/*/memory}
63 grep -q online $SYSFS/devices/system/memory/memory$1/state
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| /linux/Documentation/mm/ |
| H A D | memory-model.rst | 4 Physical Memory Model
7 Physical memory in a system may be addressed in different ways. The
8 simplest case is when the physical memory starts at address 0 and
13 different memory banks are attached to different CPUs.
15 Linux abstracts this diversity using one of the two memory models:
17 memory models it supports, what the default memory model is and
20 All the memory models track the status of physical page frames using
23 Regardless of the selected memory model, there exists one-to-one
27 Each memory model defines :c:func:`pfn_to_page` and :c:func:`page_to_pfn`
34 The simplest memory model is FLATMEM. This model is suitable for
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| H A D | hmm.rst | 2 Heterogeneous Memory Management (HMM)
5 Provide infrastructure and helpers to integrate non-conventional memory (device
6 memory like GPU on board memory) into regular kernel path, with the cornerstone
7 of this being specialized struct page for such memory (see sections 5 to 7 of
10 HMM also provides optional helpers for SVM (Share Virtual Memory), i.e.,
18 related to using device specific memory allocators. In the second section, I
22 fifth section deals with how device memory is represented inside the kernel.
28 Problems of using a device specific memory allocator
31 Devices with a large amount of on board memory (several gigabytes) like GPUs
32 have historically managed their memory through dedicated driver specific APIs.
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| H A D | numa.rst | 12 or more CPUs, local memory, and/or IO buses. For brevity and to
26 Coherent NUMA or ccNUMA systems. With ccNUMA systems, all memory is visible
30 Memory access time and effective memory bandwidth varies depending on how far
31 away the cell containing the CPU or IO bus making the memory access is from the
32 cell containing the target memory. For example, access to memory by CPUs
34 bandwidths than accesses to memory on other, remote cells. NUMA platforms
39 memory bandwidth. However, to achieve scalable memory bandwidth, system and
40 application software must arrange for a large majority of the memory references
41 [cache misses] to be to "local" memory--memory on the same cell, if any--or
42 to the closest cell with memory.
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| /linux/Documentation/ABI/testing/ |
| H A D | sysfs-devices-memory | 1 What: /sys/devices/system/memory
5 The /sys/devices/system/memory contains a snapshot of the
6 internal state of the kernel memory blocks. Files could be
9 Users: hotplug memory add/remove tools
12 What: /sys/devices/system/memory/memoryX/removable
16 The file /sys/devices/system/memory/memoryX/removable is a
17 legacy interface used to indicated whether a memory block is
19 "1" if and only if the kernel supports memory offlining.
20 Users: hotplug memory remove tools
24 What: /sys/devices/system/memory/memoryX/phys_device
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| /linux/Documentation/arch/arm64/ |
| H A D | kdump.rst | 2 crashkernel memory reservation on arm64
9 reserved memory is needed to pre-load the kdump kernel and boot such
12 That reserved memory for kdump is adapted to be able to minimally
19 Through the kernel parameters below, memory can be reserved accordingly
21 large chunk of memomy can be found. The low memory reservation needs to
22 be considered if the crashkernel is reserved from the high memory area.
28 Low memory and high memory
31 For kdump reservations, low memory is the memory area under a specific
34 vmcore dumping can be ignored. On arm64, the low memory upper bound is
37 whole system RAM is low memory. Outside of the low memory described
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| /linux/tools/testing/selftests/cgroup/ |
| H A D | test_memcontrol.c | 29 * the memory controller.
37 /* Create two nested cgroups with the memory controller enabled */ in test_memcg_subtree_control()
46 if (cg_write(parent, "cgroup.subtree_control", "+memory")) in test_memcg_subtree_control()
52 if (cg_read_strstr(child, "cgroup.controllers", "memory")) in test_memcg_subtree_control()
55 /* Create two nested cgroups without enabling memory controller */ in test_memcg_subtree_control()
70 if (!cg_read_strstr(child2, "cgroup.controllers", "memory")) in test_memcg_subtree_control()
109 current = cg_read_long(cgroup, "memory.current"); in alloc_anon_50M_check()
116 anon = cg_read_key_long(cgroup, "memory.stat", "anon "); in alloc_anon_50M_check()
143 current = cg_read_long(cgroup, "memory.current"); in alloc_pagecache_50M_check()
147 file = cg_read_key_long(cgroup, "memory.stat", "file "); in alloc_pagecache_50M_check()
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| /linux/Documentation/core-api/ |
| H A D | memory-hotplug.rst | 4 Memory hotplug
7 Memory hotplug event notifier
12 There are six types of notification defined in ``include/linux/memory.h``:
15 Generated before new memory becomes available in order to be able to
16 prepare subsystems to handle memory. The page allocator is still unable
17 to allocate from the new memory.
23 Generated when memory has successfully brought online. The callback may
24 allocate pages from the new memory.
27 Generated to begin the process of offlining memory. Allocations are no
28 longer possible from the memory but some of the memory to be offlined
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| H A D | memory-allocation.rst | 4 Memory Allocation Guide
7 Linux provides a variety of APIs for memory allocation. You can
14 Most of the memory allocation APIs use GFP flags to express how that
15 memory should be allocated. The GFP acronym stands for "get free
16 pages", the underlying memory allocation function.
19 makes the question "How should I allocate memory?" not that easy to
32 The GFP flags control the allocators behavior. They tell what memory
34 memory, whether the memory can be accessed by the userspace etc. The
39 * Most of the time ``GFP_KERNEL`` is what you need. Memory for the
40 kernel data structures, DMAable memory, inode cache, all these and
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| /linux/drivers/base/ |
| H A D | memory.c | 3 * Memory subsystem support
9 * a SPARSEMEM-memory-model system's physical memory in /sysfs.
19 #include <linux/memory.h>
29 #define MEMORY_CLASS_NAME "memory"
79 * Memory blocks are cached in a local radix tree to avoid
86 * Memory groups, indexed by memory group id (mgid).
119 /* Show the memory block ID, relative to the memory block size */
203 * they describe (they remain until the memory is unplugged), doing in memory_block_online()
204 * their initialization and accounting at memory onlining/offlining in memory_block_online()
206 * belong to the same zone as the memory they backed. in memory_block_online()
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| /linux/include/linux/ |
| H A D | memory.h | 3 * include/linux/memory.h - generic memory definition
9 * Basic handling of the devices is done in drivers/base/memory.c
12 * Memory block are exported via sysfs in the class/memory/devices/
26 * struct memory_group - a logical group of memory blocks
27 * @nid: The node id for all memory blocks inside the memory group.
28 * @blocks: List of all memory blocks belonging to this memory group.
29 * @present_kernel_pages: Present (online) memory outside ZONE_MOVABLE of this
30 * memory group.
31 * @present_movable_pages: Present (online) memory in ZONE_MOVABLE of this
32 * memory group.
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| /linux/Documentation/arch/powerpc/ |
| H A D | firmware-assisted-dump.rst | 14 - Fadump uses the same firmware interfaces and memory reservation model
16 - Unlike phyp dump, FADump exports the memory dump through /proc/vmcore
21 - Unlike phyp dump, FADump allows user to release all the memory reserved
35 - Once the dump is copied out, the memory that held the dump
44 - The first kernel registers the sections of memory with the
46 These registered sections of memory are reserved by the first
50 low memory regions (boot memory) from source to destination area.
54 The term 'boot memory' means size of the low memory chunk
56 booted with restricted memory. By default, the boot memory
58 Alternatively, user can also specify boot memory size
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| /linux/tools/perf/pmu-events/arch/arm64/arm/neoverse-n2-v2/ |
| H A D | memory.json | 4 …memory accesses issued by the CPU load store unit, where those accesses are issued due to load or …
8 …memory errors (ECC or parity) in protected CPUs RAMs. On the core, this event counts errors in the…
16 …memory accesses issued by the CPU due to load operations. The event counts any memory load access,…
20 …memory accesses issued by the CPU due to store operations. The event counts any memory store acces…
24 …"PublicDescription": "Counts the number of memory read and write accesses in a cycle that incurred…
28 …"PublicDescription": "Counts the number of memory read accesses in a cycle that incurred additiona…
32 …"PublicDescription": "Counts the number of memory write access in a cycle that incurred additional…
36 …icDescription": "Counts the number of memory read and write accesses in a cycle that are tag check…
40 …"PublicDescription": "Counts the number of memory read accesses in a cycle that are tag checked by…
44 …"PublicDescription": "Counts the number of memory write accesses in a cycle that is tag checked by…
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| /linux/tools/testing/selftests/arm64/mte/ |
| H A D | check_mmap_options.c | 75 /* Only mte enabled memory will allow tag insertion */ in check_anonymous_memory_mapping()
78 ksft_print_msg("FAIL: Insert tags on anonymous mmap memory\n"); in check_anonymous_memory_mapping()
112 /* Only mte enabled memory will allow tag insertion */ in check_file_memory_mapping()
115 ksft_print_msg("FAIL: Insert tags on file based memory\n"); in check_file_memory_mapping()
213 "Check anonymous memory with private mapping, sync error mode, mmap memory and tag check off\n"); in main()
215 …"Check file memory with private mapping, sync error mode, mmap/mprotect memory and tag check off\n… in main()
219 "Check anonymous memory with private mapping, no error mode, mmap memory and tag check off\n"); in main()
221 "Check file memory with private mapping, no error mode, mmap/mprotect memory and tag check off\n"); in main()
224 "Check anonymous memory with private mapping, sync error mode, mmap memory and tag check on\n"); in main()
226 …"Check anonymous memory with private mapping, sync error mode, mmap/mprotect memory and tag check … in main()
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| /linux/arch/powerpc/kexec/ |
| H A D | ranges.c | 46 * @mem_rngs: Memory ranges.
61 * Memory is allocated in size multiple of MEM_RANGE_CHUNK_SZ. in get_mem_rngs_size()
68 * __add_mem_range - add a memory range to memory ranges list.
69 * @mem_ranges: Range list to add the memory range to.
71 * @size: Size of the memory range to add.
73 * (Re)allocates memory, if needed.
89 pr_debug("Added memory range [%#016llx - %#016llx] at index %d\n", in __add_mem_range()
96 * __merge_memory_ranges - Merges the given memory ranges list.
140 * sort_memory_ranges - Sorts the given memory ranges list.
161 pr_debug("Memory ranges:\n"); in sort_memory_ranges()
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| /linux/Documentation/admin-guide/mm/damon/ |
| H A D | reclaim.rst | 8 be used for proactive and lightweight reclamation under light memory pressure.
10 to be selectively used for different level of memory pressure and requirements.
15 On general memory over-committed systems, proactively reclaiming cold pages
16 helps saving memory and reducing latency spikes that incurred by the direct
20 Free Pages Reporting [3]_ based memory over-commit virtualization systems are
22 memory to host, and the host reallocates the reported memory to other guests.
23 As a result, the memory of the systems are fully utilized. However, the
24 guests could be not so memory-frugal, mainly because some kernel subsystems and
25 user-space applications are designed to use as much memory as available. Then,
26 guests could report only small amount of memory as free to host, results in
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| /linux/drivers/gpu/drm/nouveau/nvkm/core/ |
| H A D | memory.c | 24 #include <core/memory.h>
30 nvkm_memory_tags_put(struct nvkm_memory *memory, struct nvkm_device *device, in nvkm_memory_tags_put() argument
39 kfree(memory->tags); in nvkm_memory_tags_put()
40 memory->tags = NULL; in nvkm_memory_tags_put()
48 nvkm_memory_tags_get(struct nvkm_memory *memory, struct nvkm_device *device, in nvkm_memory_tags_get() argument
56 if ((tags = memory->tags)) { in nvkm_memory_tags_get()
57 /* If comptags exist for the memory, but a different amount in nvkm_memory_tags_get()
84 * As memory can be mapped in multiple places, we still in nvkm_memory_tags_get()
94 *ptags = memory->tags = tags; in nvkm_memory_tags_get()
101 struct nvkm_memory *memory) in nvkm_memory_ctor() argument
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| /linux/mm/ |
| H A D | Kconfig | 3 menu "Memory Management options"
16 bool "Support for paging of anonymous memory (swap)"
22 used to provide more virtual memory than the actual RAM present
33 compress them into a dynamically allocated RAM-based memory pool.
49 bool "Shrink the zswap pool on memory pressure"
55 written back to the backing swap device) on memory pressure.
60 and consume memory indefinitely.
207 zsmalloc is a slab-based memory allocator designed to store
246 bool "Configure for minimal memory footprint"
250 Configures the slab allocator in a way to achieve minimal memory
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| /linux/drivers/memory/tegra/ |
| H A D | Kconfig | 3 bool "NVIDIA Tegra Memory Controller support"
8 This driver supports the Memory Controller (MC) hardware found on
14 tristate "NVIDIA Tegra20 External Memory Controller driver"
21 This driver is for the External Memory Controller (EMC) found on
23 This driver is required to change memory timings / clock rate for
24 external memory.
27 tristate "NVIDIA Tegra30 External Memory Controller driver"
33 This driver is for the External Memory Controller (EMC) found on
35 This driver is required to change memory timings / clock rate for
36 external memory.
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| /linux/tools/testing/memblock/tests/ |
| H A D | basic_api.c | 17 ASSERT_NE(memblock.memory.regions, NULL); in memblock_initialization_check()
18 ASSERT_EQ(memblock.memory.cnt, 0); in memblock_initialization_check()
19 ASSERT_EQ(memblock.memory.max, EXPECTED_MEMBLOCK_REGIONS); in memblock_initialization_check()
20 ASSERT_EQ(strcmp(memblock.memory.name, "memory"), 0); in memblock_initialization_check()
24 ASSERT_EQ(memblock.memory.max, EXPECTED_MEMBLOCK_REGIONS); in memblock_initialization_check()
36 * A simple test that adds a memory block of a specified base address
37 * and size to the collection of available memory regions (memblock.memory).
38 * Expect to create a new entry. The region counter and total memory get
45 rgn = &memblock.memory.regions[0]; in memblock_add_simple_check()
60 ASSERT_EQ(memblock.memory.cnt, 1); in memblock_add_simple_check()
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| /linux/drivers/cxl/ |
| H A D | Kconfig | 15 memory targets, the CXL.io protocol is equivalent to PCI Express.
25 The CXL specification defines a "CXL memory device" sub-class in the
26 PCI "memory controller" base class of devices. Device's identified by
28 memory to be mapped into the system address map (Host-managed Device
29 Memory (HDM)).
31 Say 'y/m' to enable a driver that will attach to CXL memory expander
32 devices enumerated by the memory device class code for configuration
39 bool "RAW Command Interface for Memory Devices"
52 potential impact to memory currently in use by the kernel.
65 Enable support for host managed device memory (HDM) resources
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| /linux/Documentation/userspace-api/media/v4l/ |
| H A D | dev-mem2mem.rst | 6 Video Memory-To-Memory Interface
9 A V4L2 memory-to-memory device can compress, decompress, transform, or
10 otherwise convert video data from one format into another format, in memory.
11 Such memory-to-memory devices set the ``V4L2_CAP_VIDEO_M2M`` or
12 ``V4L2_CAP_VIDEO_M2M_MPLANE`` capability. Examples of memory-to-memory
16 A memory-to-memory video node acts just like a normal video node, but it
17 supports both output (sending frames from memory to the hardware)
19 memory) stream I/O. An application will have to setup the stream I/O for
23 Memory-to-memory devices function as a shared resource: you can
32 One of the most common memory-to-memory device is the codec. Codecs
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