Linux Kernel Architecture

Chapter3:MemoryManagement Since future hardware implementations might support larger physical address spaces, it is not possible ...

Chapter3:MemoryManagement include/asm-x86/pgtable_64.h #define __AC(X,Y) (X##Y) #define _AC(X,Y) __AC(X,Y) #define __PAGE_OFFSET ...

Chapter3:MemoryManagement but it is ensured that the resulting address__START_KERNELis aligned with__KERNEL_ALIGN.Theregion rese ...

Chapter3:MemoryManagement Reservation is implemented in a CPU-independent way on UMA systems (NUMA systems employ architecture-s ...

Chapter3:MemoryManagement which callssetup_bootmem_allocatorto initialize the bootmem allocator, whereas AMD64 uses contig_initm ...

Chapter3:MemoryManagement Based on this information,setup_bootmem_allocatoris then responsible to initiate all necessary steps t ...

Chapter3:MemoryManagement Interfaceto the Kernel Allocating Memory The kernel provides a variety of functions for reserving memo ...

Chapter3:MemoryManagement The desired allocation size (x)isforwardedunchangedto__alloc_bootmem, but there are two options for al ...

Chapter3:MemoryManagement intended for basic data structures that are needed throughout kernel run time and are therefore never ...

Chapter3:MemoryManagement initialization functions is to keep the data in a specific part of the kernel image that can be comple ...

Chapter3:MemoryManagement wolfgang@meitner>dmesg ... Freeing unused kernel memory: 308k freed ... In comparison with today’s ...

Chapter3:MemoryManagement <mmzone.h> #ifndef CONFIG_FORCE_MAX_ZONEORDER #define MAX_ORDER 11 #else #define MAX_ORDER CONFI ...

Chapter3:MemoryManagement Memory management based on the buddy system isconcentrated on a single memory zone of a node, for inst ...

Chapter3:MemoryManagement 48 59 36 24 12 0 47 35 23 11 Figure 3-24: Fragmentation of physical memory. Assume that the memory con ...

Chapter3:MemoryManagement cannot be moved to an arbitrary location. Therefore, the kernel’s approach isanti-fragmentation:Tryto ...

Chapter3:MemoryManagement Data Structure Setup Although the anti-fragmentation technique used by the kernel is highly effective, ...

Chapter3:MemoryManagement The data structure is mostly self-explanatory: When the kernel wants to allocate un-movable pages, but ...

Chapter3:MemoryManagement If page mobility has been disabled, all pages will be kept in the unmovable zone. Otherwise, the retur ...

Chapter3:MemoryManagement Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10 Node 0, zone DMA, type Unmovable 0 0 ...

Chapter3:MemoryManagement Naturally, not too many movable allocations willhave been performed during boot, so chances are good t ...