Edit

Memory

Basic

https://en.wikipedia.org/wiki/PCI_configuration_space

The system's firmware, device drivers or the operating system program the Base Address Registers (commonly called BARs) to inform the device of its address mapping by writing configuration commands to the PCI controller.

https://stackoverflow.com/questions/1477885 Anon blocks are "large" blocks allocated via malloc or mmap

https://stackoverflow.com/questions/79923 The stack is the memory set aside as scratch space for a thread of execution. The heap is memory set aside for dynamic allocation. Each thread gets a stack, while there's typically only one heap for the application

https://linux-mm.org/LinuxMMDocumentation

cgroup

http://elixir.free-electrons.com/linux/latest/source/Documentation/cgroup-v1/memory.txt

Memory Management Unit (MMU)

https://cseweb.ucsd.edu/classes/su09/cse120/lectures/Lecture7.pdf

kmalloc & vmalloc

https://static.lwn.net/images/pdf/LDD3/ch08.pdf

System Management Mode (SMM)

http://invisiblethingslab.com/resources/misc09/smm_cache_fun.pdf

Memory Map

https://firmware.intel.com/sites/default/files/resources/A_Tour_Beyond_BIOS_Memory_Map_in UEFI_BIOS.pdf

system memory

Legacy Region

Firmware Perspective - Platform Initialization (PI) specification

Pre-EFI-initialization (PEI) phase

no memory map term in PEI phase. The “memory map” concept is reported by in PEI Hand-of-Block (HOB).

Driver eXecution Environment (DXE) Phase

Global Coherency Domain Services (GCD) are used to manage the memory and I/O resources visible to the boot processor, including GCD memory space map, and GCD IO space map.

OS Perspective

GetMemoryMap() interface returns an array of UEFI memory descriptors. no UEFI memory map for S3 resume, because S3 resume only has PEI phase. The memory map should NOT be changed in S4 resume phase, because OS restores the system memory from disk directly.

legacy ACPI specification: INT15 E820H function call, or E820 table.

The difference is that E820 table does not have runtime concept, so memory mapped I/O and memory mapped I/O port space allowed for virtual mode calls to UEFI run-time functions does not exist.

dmesg

/proc/iomem

with related e820/efi/ACPI dmesg

free

drop_caches

/proc/meminfo

https://www.kernel.org/doc/Documentation/filesystems/proc.txt https://github.com/torvalds/linux/blob/master/fs/proc/meminfo.c#L69 https://access.redhat.com/solutions/406773

/proc/vmallocinfo

/proc/PID/maps

pmap

Global Graphics Translation Table (GTT)

address mapping from the GPU virtual address space to physical addresses.

KVM MMU Virtualization

https://events.static.linuxfound.org/slides/2011/linuxcon-japan/lcj2011_guangrong.pdf

GFN: Guest Frame Number PFN: Host Page Frame Number

GPA: Guest Physical Address HVA: Host Virtual Address HPA: Host Physical Address

Hard MMU • NPT on SVM from AMD • EPT on VMX from Intel

Hardware

lshw -C memory

Numa

numactl -H available: 2 nodes (0-1) node 0 cpus: 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 node 0 size: 16053 MB node 0 free: 149 MB node 1 cpus: 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 node 1 size: 16122 MB node 1 free: 78 MB node distances: node 0 1 0: 10 20 1: 20 10

Hugepages

https://wiki.debian.org/Hugepages#Enabling_HugeTlbPage bigger pages, the CPU/OS have less entries to look-up

sudo sysctl -w vm.nr_hugepages=128

/etc/security/limits.conf # Exit and re-login to take effect.

  • soft memlock 262144

  • hard memlock 262144

    vi /root/.bashrc ulimit -u unlimited

    apt install hugepages -y hugeadm --pool-list Size Minimum Current Maximum Default 2097152 0 0 0 * 1073741824 0 0 0

    grep Huge /proc/meminfo AnonHugePages: 18466816 kB ShmemHugePages: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB Hugetlb: 0 kB

    grep -R "" /sys/kernel/mm/hugepages/ /proc/sys/vm/huge /sys/kernel/mm/hugepages/hugepages-2048kB/free_hugepages:0 /sys/kernel/mm/hugepages/hugepages-2048kB/resv_hugepages:0 /sys/kernel/mm/hugepages/hugepages-2048kB/surplus_hugepages:0 /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages_mempolicy:0 /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/kernel/mm/hugepages/hugepages-2048kB/nr_overcommit_hugepages:0 /sys/kernel/mm/hugepages/hugepages-1048576kB/free_hugepages:0 /sys/kernel/mm/hugepages/hugepages-1048576kB/resv_hugepages:0 /sys/kernel/mm/hugepages/hugepages-1048576kB/surplus_hugepages:0 /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages_mempolicy:0 /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages:0 /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_overcommit_hugepages:0 /proc/sys/vm/hugetlb_shm_group:0 /proc/sys/vm/nr_hugepages:0 /proc/sys/vm/nr_hugepages_mempolicy:0 /proc/sys/vm/nr_overcommit_hugepages:0

PreviouskernelNextnw

Last updated

Was this helpful?