Linux mm相关的问题

[S]为什么High MEM是从896M開始的？

As the running kernel needs these functions, a region of at least

VMALLOC_RESERVE will be reserved at the top of the address space.

VMALLOC_RESERVE is architecture specific but on the x86, it is defined

as 128MiB. This is why ZONE_NORMAL is generally referred to being only

896MiB in size; it is the 1GiB of the upper potion of the linear

address space minus the minimum 128MiB that is reserved for the

vmalloc region.

kernel/process page table是怎么切换的？

物理内存的分部。kernel reserve了哪些，剩下的是怎么给process的。

[S]kernel page table什么时候设置好的？

内核页表成长记

[S]内核页表长什么样子

内核页表成长记

[S]4.9内核最大支持内存为多少？

64 TB

mm.txt

ffff880000000000 - ffffc7ffffffffff (=64 TB) direct mapping of all phys. memory

[S]内核态物理地址和虚拟地址转化过程

_pa() _va()

init_range_memory_mapping()为什么要检測是否重叠

        /*
         * if it is overlapping with brk pgt, we need to
         * alloc pgt buf from memblock instead.
         */
        can_use_brk_pgt = max(start, (u64)pgt_buf_end<<PAGE_SHIFT) >=
                    min(end, (u64)pgt_buf_top<<PAGE_SHIFT);

启用了sparse_mem后，每一个node至少是一个section大小么？

static void set_section_nid(unsigned long section_nr, int nid)
{
    section_to_node_table[section_nr] = nid;
}

那需不须要再alloc node_data的时候检測这个node的大小是否符合要求？

high men?

high map? 内核中还有什么high的？都一样吗？

• high mem = 896M以上
• cleanup_highmap()，清理了__START_KERNEL_map以上的映射。这是个虚拟地址的概念。

• is_highmem_idx(), ZONE_HIGHMEM。这个感觉是物理地址的概念。

[S]how pfn_to_page(), page_to_pfn(), virt_to_page(), page_address() works?

page_to_pfn/pfn_to_page

virt_to_page

内核是否支持Numa overlap的内存布局？

据说能够

Another advantage is that sparse

doesn’t require each NUMA node’s

ranges to be contiguous.

以及对memory hotplug的一个文章

MOVABLE_ZONE是不是会overlap其它zone？

如今不会，据说Michal以后会同意overlap。

当然我没有想好overlap后会怎么个运作。