| /Linux-v5.15/Documentation/admin-guide/mm/ |
| D | memory-hotplug.rst | 4 Memory Hot(Un)Plug
7 This document describes generic Linux support for memory hot(un)plug with
15 Memory hot(un)plug allows for increasing and decreasing the size of physical
16 memory available to a machine at runtime. In the simplest case, it consists of
20 Memory hot(un)plug is used for various purposes:
22 - The physical memory available to a machine can be adjusted at runtime, up- or
23 downgrading the memory capacity. This dynamic memory resizing, sometimes
28 example is replacing failing memory modules.
30 - Reducing energy consumption either by physically unplugging memory modules or
31 by logically unplugging (parts of) memory modules from Linux.
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| D | concepts.rst | 7 The memory management in Linux is a complex system that evolved over the
9 systems from MMU-less microcontrollers to supercomputers. The memory
18 Virtual Memory Primer
21 The physical memory in a computer system is a limited resource and
22 even for systems that support memory hotplug there is a hard limit on
23 the amount of memory that can be installed. The physical memory is not
29 All this makes dealing directly with physical memory quite complex and
30 to avoid this complexity a concept of virtual memory was developed.
32 The virtual memory abstracts the details of physical memory from the
34 physical memory (demand paging) and provides a mechanism for the
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| D | numaperf.rst | 7 Some platforms may have multiple types of memory attached to a compute
8 node. These disparate memory ranges may share some characteristics, such
12 A system supports such heterogeneous memory by grouping each memory type
14 characteristics. Some memory may share the same node as a CPU, and others
15 are provided as memory only nodes. While memory only nodes do not provide
18 nodes with local memory and a memory only node for each of compute node::
29 A "memory initiator" is a node containing one or more devices such as
30 CPUs or separate memory I/O devices that can initiate memory requests.
31 A "memory target" is a node containing one or more physical address
32 ranges accessible from one or more memory initiators.
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| /Linux-v5.15/tools/testing/selftests/memory-hotplug/ |
| 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-v5.15/Documentation/admin-guide/cgroup-v1/ |
| D | memory.rst | 2 Memory Resource Controller
12 The Memory Resource Controller has generically been referred to as the
13 memory controller in this document. Do not confuse memory controller
14 used here with the memory controller that is used in hardware.
17 When we mention a cgroup (cgroupfs's directory) with memory controller,
18 we call it "memory cgroup". When you see git-log and source code, you'll
22 Benefits and Purpose of the memory controller
25 The memory controller isolates the memory behaviour of a group of tasks
27 uses of the memory controller. The memory controller can be used to
30 Memory-hungry applications can be isolated and limited to a smaller
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| /Linux-v5.15/Documentation/vm/ |
| D | memory-model.rst | 6 Physical Memory Model
9 Physical memory in a system may be addressed in different ways. The
10 simplest case is when the physical memory starts at address 0 and
15 different memory banks are attached to different CPUs.
17 Linux abstracts this diversity using one of the two memory models:
19 memory models it supports, what the default memory model is and
22 All the memory models track the status of physical page frames using
25 Regardless of the selected memory model, there exists one-to-one
29 Each memory model defines :c:func:`pfn_to_page` and :c:func:`page_to_pfn`
36 The simplest memory model is FLATMEM. This model is suitable for
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| D | hmm.rst | 4 Heterogeneous Memory Management (HMM)
7 Provide infrastructure and helpers to integrate non-conventional memory (device
8 memory like GPU on board memory) into regular kernel path, with the cornerstone
9 of this being specialized struct page for such memory (see sections 5 to 7 of
12 HMM also provides optional helpers for SVM (Share Virtual Memory), i.e.,
20 related to using device specific memory allocators. In the second section, I
24 fifth section deals with how device memory is represented inside the kernel.
30 Problems of using a device specific memory allocator
33 Devices with a large amount of on board memory (several gigabytes) like GPUs
34 have historically managed their memory through dedicated driver specific APIs.
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| D | numa.rst | 14 or more CPUs, local memory, and/or IO buses. For brevity and to
28 Coherent NUMA or ccNUMA systems. With ccNUMA systems, all memory is visible
32 Memory access time and effective memory bandwidth varies depending on how far
33 away the cell containing the CPU or IO bus making the memory access is from the
34 cell containing the target memory. For example, access to memory by CPUs
36 bandwidths than accesses to memory on other, remote cells. NUMA platforms
41 memory bandwidth. However, to achieve scalable memory bandwidth, system and
42 application software must arrange for a large majority of the memory references
43 [cache misses] to be to "local" memory--memory on the same cell, if any--or
44 to the closest cell with memory.
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| /Linux-v5.15/Documentation/ABI/testing/ |
| 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-v5.15/tools/testing/selftests/cgroup/ |
| D | test_memcontrol.c | 25 * the memory controller.
33 /* Create two nested cgroups with the memory controller enabled */ in test_memcg_subtree_control()
42 if (cg_write(parent, "cgroup.subtree_control", "+memory")) in test_memcg_subtree_control()
48 if (cg_read_strstr(child, "cgroup.controllers", "memory")) in test_memcg_subtree_control()
51 /* Create two nested cgroups without enabling memory controller */ in test_memcg_subtree_control()
66 if (!cg_read_strstr(child2, "cgroup.controllers", "memory")) in test_memcg_subtree_control()
100 current = cg_read_long(cgroup, "memory.current"); in alloc_anon_50M_check()
107 anon = cg_read_key_long(cgroup, "memory.stat", "anon "); in alloc_anon_50M_check()
134 current = cg_read_long(cgroup, "memory.current"); in alloc_pagecache_50M_check()
138 file = cg_read_key_long(cgroup, "memory.stat", "file "); in alloc_pagecache_50M_check()
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| /Linux-v5.15/Documentation/core-api/ |
| 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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| 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-v5.15/Documentation/devicetree/bindings/reserved-memory/ |
| D | reserved-memory.txt | 1 *** Reserved memory regions ***
3 Reserved memory is specified as a node under the /reserved-memory node.
4 The operating system shall exclude reserved memory from normal usage
6 normal use) memory regions. Such memory regions are usually designed for
9 Parameters for each memory region can be encoded into the device tree
12 /reserved-memory node
19 /reserved-memory/ child nodes
21 Each child of the reserved-memory node specifies one or more regions of
22 reserved memory. Each child node may either use a 'reg' property to
23 specify a specific range of reserved memory, or a 'size' property with
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| /Linux-v5.15/include/linux/ |
| D | tee_drv.h | 23 #define TEE_SHM_MAPPED BIT(0) /* Memory mapped by the kernel */
24 #define TEE_SHM_DMA_BUF BIT(1) /* Memory with dma-buf handle */
25 #define TEE_SHM_EXT_DMA_BUF BIT(2) /* Memory with dma-buf handle */
26 #define TEE_SHM_REGISTER BIT(3) /* Memory registered in secure world */
27 #define TEE_SHM_USER_MAPPED BIT(4) /* Memory mapped in user space */
28 #define TEE_SHM_POOL BIT(5) /* Memory allocated from pool */
29 #define TEE_SHM_KERNEL_MAPPED BIT(6) /* Memory mapped in kernel space */
30 #define TEE_SHM_PRIV BIT(7) /* Memory private to TEE driver */
40 * @list_shm: List of shared memory object owned by this context
45 * shared memory release.
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| 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/
27 * struct memory_group - a logical group of memory blocks
28 * @nid: The node id for all memory blocks inside the memory group.
29 * @blocks: List of all memory blocks belonging to this memory group.
30 * @present_kernel_pages: Present (online) memory outside ZONE_MOVABLE of this
31 * memory group.
32 * @present_movable_pages: Present (online) memory in ZONE_MOVABLE of this
33 * memory group.
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| D | dma-buf-map.h | 3 * Pointer to dma-buf-mapped memory, plus helpers.
15 * Calling dma-buf's vmap operation returns a pointer to the buffer's memory.
17 * I/O operations or memory load/store operations. For example, copying to
18 * system memory could be done with memcpy(), copying to I/O memory would be
23 * void *vaddr = ...; // pointer to system memory
26 * void *vaddr_iomem = ...; // pointer to I/O memory
32 * system or I/O memory and a flag that signals the required method of
34 * to access the buffer's memory in the correct way.
38 * among devices, drivers have to know the location of the memory to access
49 * dma_buf_map_set_vaddr(). These helpers will set an address in system memory.
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| /Linux-v5.15/drivers/base/ |
| 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 first physical section index (number) of this memory block.
191 * they describe (they remain until the memory is unplugged), doing in memory_block_online()
192 * their initialization and accounting at memory onlining/offlining in memory_block_online()
194 * belong to the same zone as the memory they backed. in memory_block_online()
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| /Linux-v5.15/drivers/gpu/drm/nouveau/nvkm/core/ |
| 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-v5.15/tools/testing/selftests/arm64/mte/ |
| D | check_mmap_options.c | 76 /* Only mte enabled memory will allow tag insertion */ in check_anonymous_memory_mapping()
79 ksft_print_msg("FAIL: Insert tags on anonymous mmap memory\n"); in check_anonymous_memory_mapping()
113 /* Only mte enabled memory will allow tag insertion */ in check_file_memory_mapping()
116 ksft_print_msg("FAIL: Insert tags on file based memory\n"); in check_file_memory_mapping()
214 "Check anonymous memory with private mapping, sync error mode, mmap memory and tag check off\n"); in main()
216 …"Check file memory with private mapping, sync error mode, mmap/mprotect memory and tag check off\n… in main()
220 "Check anonymous memory with private mapping, no error mode, mmap memory and tag check off\n"); in main()
222 "Check file memory with private mapping, no error mode, mmap/mprotect memory and tag check off\n"); in main()
225 "Check anonymous memory with private mapping, sync error mode, mmap memory and tag check on\n"); in main()
227 …"Check anonymous memory with private mapping, sync error mode, mmap/mprotect memory and tag check … in main()
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| /Linux-v5.15/mm/ |
| D | Kconfig | 3 menu "Memory Management options"
10 prompt "Memory model"
16 Linux manages its memory internally. Most users will
21 bool "Flat Memory"
30 spaces and for features like NUMA and memory hotplug,
31 choose "Sparse Memory".
33 If unsure, choose this option (Flat Memory) over any other.
36 bool "Sparse Memory"
40 memory hot-plug systems. This is normal.
43 holes is their physical address space and allows memory
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| /Linux-v5.15/Documentation/powerpc/ |
| 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-v5.15/drivers/memory/tegra/ |
| 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"
20 This driver is for the External Memory Controller (EMC) found on
22 This driver is required to change memory timings / clock rate for
23 external memory.
26 tristate "NVIDIA Tegra30 External Memory Controller driver"
31 This driver is for the External Memory Controller (EMC) found on
33 This driver is required to change memory timings / clock rate for
34 external memory.
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| /Linux-v5.15/Documentation/userspace-api/media/v4l/ |
| 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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| /Linux-v5.15/Documentation/dev-tools/ |
| D | kasan.rst | 7 KernelAddressSANitizer (KASAN) is a dynamic memory safety error detector
12 3. hardware tag-based KASAN (based on hardware memory tagging).
14 Generic KASAN is mainly used for debugging due to a large memory overhead.
16 memory overhead that allows using it with real workloads. Hardware tag-based
17 KASAN comes with low memory and performance overheads and, therefore, can be
18 used in production. Either as an in-field memory bug detector or as a security
22 validity checks before every memory access and, therefore, require a compiler
32 still requires a compiler version that supports memory tagging instructions.
35 Both software KASAN modes work with SLUB and SLAB memory allocators,
127 Memory state around the buggy address:
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| D | kmemleak.rst | 1 Kernel Memory Leak Detector
4 Kmemleak provides a way of detecting possible kernel memory leaks in a
9 Valgrind tool (``memcheck --leak-check``) to detect the memory leaks in
16 thread scans the memory every 10 minutes (by default) and prints the
22 To display the details of all the possible scanned memory leaks::
26 To trigger an intermediate memory scan::
30 To clear the list of all current possible memory leaks::
41 Memory scanning parameters can be modified at run-time by writing to the
51 start the automatic memory scanning thread (default)
53 stop the automatic memory scanning thread
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